Related
What is want to do is the following:
declare #Count numeric (10)
set #Count = 0
set #Count = (select count(*) from FILENAME where COLUMNNAME like '%e%')
print(#tel)
I want it do be done on a few files that have a lot of columns and have a total count for all the columns, so my idea was to get a columnlist of each file by doint something like:
select * from sys.columns
where object_id = ( select object_id from sys.objects where name = 'FILENAME')
Now the easiest way i thought would be using a cursor and have the #Counts added up there in another variable. But the problem i am having is that when COLUMNNAME is in a variable in the cursor i can only (as far as i know) make the query like:
declare #SQL varchar(max)
set #SQL = #SQL + 'set #Count = (select count(*) from FILENAME where '
+ #columnname + ' like ''%e%'' )'
set #tot_Count = #tot_Count + #Count
But as I understand from reading around dynamic sql inside a cursor is a big no.
And though when i see the "print (sql)" the queries seem to be right it doesnt seem to work indeed in a cursos.
Is there another way to get the results i want?
Or am i doing something wrong here?
For reference, this was the idea i had in total:
DECLARE #columnname VARCHAR(50)
DECLARE #tot_Count NUMERIC(10), #Count NUMERIC(10)
set #tot_Count = 0
DECLARE MyCursor CURSOR FOR
SELECT name
from sys.columns
where object_id = ( select object_id from sys.objects where name = 'FILENAME' )
open MyCursor
FETCH NEXT FROM MyCursor INTO #columnname
WHILE ##FETCH_STATUS = 0
BEGIN
declare #SQL varchar(max)
set #SQL =''
set #Count = 0
set #SQL = #SQL + 'set #teller = (select count(*) from FILENAME where ' + #columnname + ' like ''%e%'' )'
print (#SQL)
exec (#SQL)
set #tot_Count = #tot_Count + #Count
FETCH NEXT FROM MyCursor into #name
END
CLOSE MyCursor
DEALLOCATE MyCursor
print (#tot_teller)
Variant 1: You can use dynamic variable instead of cursor operation.
declare #qry varchar(max)
select #qry = isnull(#qry + ' union all', '') + ' select count(*) cnt from ' + object_name(object_id) + ' where ' + name + ' like ''%e%'''
from sys.columns
where object_id = object_id('YourTableName')
set #qry = 'select sum(cnt) from (' + #qry + ') q'
print #qry
exec (#qry)
It's shorter, better, but exec is limited by 4000 chars.
Variant 2: Or you can use your cursor and via dynamic qry insert into your preprepared temp table.
if object_id('tempdb..#tmptbl') is not null drop table #tmptbl
create table #tmptbl (cnt int not null)
declare #colqry varchar(800)
declare mycursor cursor for
select 'insert into #tmptbl (cnt) select count(*) cnt from ' + object_name(object_id) + ' where ' + name + ' like ''%e%'''
from sys.columns
where object_id = object_id('YourTableName')
open mycursor
fetch next from mycursor into #colqry
while ##fetch_status = 0
begin
print #colqry
exec (#colqry)
fetch next from mycursor into #colqry
end
close mycursor
deallocate mycursor
select sum(cnt) from #tmptbl
DECLARE #tot_Count int = 0
DECLARE #Separator varchar(1) = ','
DECLARE #Position INT = 1
DECLARE #ColumnNameList varchar(MAX)
DECLARE #ColumnName varchar(1000)
DECLARE #SQL varchar(max) = ''
SET #ColumnNameList = STUFF(( SELECT name
from sys.columns
where object_id in ( select object_id from sys.objects where name = 'FILENAME' ) FOR XML PATH('')),1,1,'')+','
--print #FileNameList
WHILE (CHARINDEX(#Separator,#ColumnNameList,#Position)!=0)
BEGIN
SET #ColumnName = SUBSTRING(#ColumnNameList,#Position,CHARINDEX(#Separator,#ColumnNameList,#Position)-#Position)
SET #SQL = #SQL + 'set #tot_Count = (select count(*) from FILENAME where ' + #ColumnName + ' like ''%e%'' )'
-- print (#SQL)
EXEC (#SQL)
SET #tot_Count = #tot_Count + #tot_Count
SET #Position = CHARINDEX(#Separator,#ColumnNameList,#Position)+1
END
PRINT (#tot_Count)
The script below shows an example query for data that have been converted from lower case, but it only changed the data on one column in the table.
Use MYF601T
Go
UPDATE ROAD_LINE
SET NAM = UPPER(NAM)
However, the following script that I'm trying to write is to convert all on all columns on all tables, but the result generated with errors.
Use MYF601T
Go
UPDATE INFORMATION_SCHEMA.TABLES
SET INFORMATION_SCHEMA.TABLES.TABLE_SCHEMA = UPPER(INFORMATION_SCHEMA.TABLES.TABLE_SCHEMA
How to do this for all tables and all columns inside?
If for whather reasons you want to convert your tables names to Upper case, you can:
use a cursor that will select the tables you want to rename
loop through the table list
rename it using sp_rename or update it
Note that you have to update the Select in the cursor to suit your needs (select column or table name you want, ...)
This will rename tables:
declare #TABLE_NAME sysname, #TABLE_SCHEMA sysname
declare #TABLE sysname, #newName sysname
declare table_cursor Cursor
For Select TABLE_NAME, TABLE_SCHEMA From INFORMATION_SCHEMA.TABLES Where TABLE_NAME like 'xyz%' -- and TABLE_SCHEMA like ...
open table_cursor
Fetch Next From table_cursor Into #TABLE_NAME, #TABLE_SCHEMA;
While ##FETCH_STATUS = 0
Begin
Set #TABLE = quotename(UPPER(#TABLE_SCHEMA)) + '.' + quotename(UPPER(#TABLE_NAME))
Set #newName = UPPER(#TABLE_NAME)
print 'rename ' + #TABLE + ' to ' + #newName
-- uncomment next like if you really want to rename them
--exec sp_rename #TABLE, #newName
Fetch Next From table_cursor Into #TABLE_NAME, #TABLE_SCHEMA;
End
Close table_cursor
Deallocate table_cursor
If you want to update all columns xyz in table zyx, you can use this:
declare #TABLE_NAME sysname, #TABLE_SCHEMA sysname, #COLUMN_NAME sysname
declare #TABLE sysname, #sql nvarchar(max)
declare table_cursor Cursor
For Select TABLE_NAME, TABLE_SCHEMA, COLUMN_NAME From INFORMATION_SCHEMA.COLUMNS
Where COLUMN_NAME like 'xxx' -- and data_type '' ... and TABLE_NAME like 'xyz%' ... and TABLE_SCHEMA like ...
open table_cursor
Fetch Next From table_cursor Into #TABLE_NAME, #TABLE_SCHEMA, #COLUMN_NAME;
While ##FETCH_STATUS = 0
Begin
Set #TABLE = quotename(#TABLE_SCHEMA) + '.' + quotename(#TABLE_NAME)
set #sql = 'Update ' + #TABLE + ' set ' + #COLUMN_NAME + ' = UPPER(' + #COLUMN_NAME + ')'
print #sql
-- uncomment next like if you really want to execute them
--exec sp_executesql #sql
Fetch Next From table_cursor Into #TABLE_NAME, #TABLE_SCHEMA, #COLUMN_NAME;
End
Close table_cursor
Deallocate table_cursor
Use a dynamic query to update all the column content to upper case.
Query
declare #query varchar(max)
select #query =
stuff
(
(
select ';update ' + table_name + ' ' +
'set ' + column_name + ' = upper(' + column_name + ')'
from information_schema.columns
where table_name = 'ROAD_LINE'
order by table_name,column_name
for xml path('')
)
, 1, 1, '')
execute(#query);
I am looking for a script which finds and replaces all fields of type string within a DB with specified text.
The script would for example take the following parameters:
Search for: null
Replace with: empty-string
The primary string data types in SQL Server: Varchar, NVarchar, Text.
This script would then comb through all string based table data and look for in this case null and replace it with a empty string.
Ok I've put together the following code in the meantime.
-- Specify 'dbo' for all tables
DECLARE #schemaName VARCHAR(5) = 'dbo'
BEGIN
DECLARE #tableName VARCHAR(255) -- table name
DECLARE #tableID INT -- table id (aka syst.table.object_id)
DECLARE table_cursor CURSOR FOR
SELECT T.object_id AS TableID, T.name AS TableName FROM sys.tables T
INNER JOIN sys.schemas S ON S.schema_id = T.schema_id
WHERE S.name = #schemaName
OPEN table_cursor
FETCH NEXT FROM table_cursor INTO #tableID, #tableName
WHILE ##FETCH_STATUS = 0
BEGIN
-- construct each tables queries
DECLARE #totalColumnsFound INT = (SELECT COUNT(*) FROM sys.columns C WHERE OBJECT_ID = #tableID
-- text and nvarchar column data types chosen for me (if you need more like ntext, varcahr see sys.types for their ids)
AND (C.system_type_id = 35 OR c.system_type_id = 231))
IF (#totalColumnsFound > 0)
BEGIN
DECLARE #tableUpdateQuery VARCHAR(MAX) = 'update ' + #schemaName + '.' + #tableName + ' set ';
DECLARE #columnName VARCHAR(255) -- column name
DECLARE column_cursor CURSOR FOR
SELECT C.name AS ColumnName FROM sys.columns C WHERE OBJECT_ID = #tableID
-- text and nvarchar column data types chosen for me (if you need more like ntext, varcahr see sys.types for their ids)
AND (C.system_type_id = 35 OR c.system_type_id = 231)
OPEN column_cursor
FETCH NEXT FROM column_cursor INTO #columnName
WHILE ##FETCH_STATUS = 0
BEGIN
-- construct the columns for the update query, piece by piece.
-- This is also where you can apply your logic for how to handle the string update.
-- I am trimming string and updating nulls to empty strings here.
SET #tableUpdateQuery = #tableUpdateQuery + ' ' + #columnName + ' = ltrim(rtrim(isnull(' + #columnName + ',''''))),'
FETCH NEXT FROM column_cursor INTO #columnName
END
CLOSE column_cursor
DEALLOCATE column_cursor
-- trim last comma from string
SET #tableUpdateQuery = LEFT(#tableUpdateQuery, LEN(#tableUpdateQuery) - 1)
/** debuging purposes **
print 'Updating table --> ' + #tableName
print #tableUpdateQuery
print ' '
*/
-- execute dynamic sql
EXEC(#tableUpdateQuery)
END
FETCH NEXT FROM table_cursor INTO #tableID, #tableName
END
CLOSE table_cursor
DEALLOCATE table_cursor
END
--GO
this should help you:
/*
Author: sqiller
Description: Searches for a value to replace in all columns from all tables
USE: EXEC dbo.usp_Update_AllTAbles 'work', 'sqiller', 1
#search = Value to look for Replace
#newvalue = the value that will replace #search
#Test = If set to 1, it will only PRINT the UPDATE statement instead of EXEC, useful to see
what is going to update before.
*/
CREATE PROCEDURE dbo.usp_Update_AllTAbles(
#search varchar(100),
#newvalue varchar(100),
#Test bit)
AS
BEGIN
IF NOT EXISTS (select 1 from INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'Tables_to_Update')
BEGIN
CREATE TABLE dbo.Tables_to_Update(
Table_name varchar(100),
Column_name varchar(100),
recordsToUpdate int
)
END
DECLARE #table varchar(100)
DECLARE #column varchar(100)
DECLARE #SQL varchar(max)
SELECT TABLE_SCHEMA+'.'+TABLE_NAME as Table_Name, 0 as Processed INTO #tables from information_schema.tables WHERE TABLE_TYPE != 'VIEW'
WHILE EXISTS (select * from #tables where processed = 0)
BEGIN
SELECT top 1 #table = table_name from #tables where processed = 0
SELECT column_name, 0 as Processed INTO #columns from information_schema.columns where TABLE_SCHEMA+'.'+TABLE_NAME = #table
WHILE EXISTS (SELECT * from #columns where processed = 0)
BEGIN
SELECT top 1 #column = COLUMN_NAME from #columns where processed = 0
SET #SQL = 'INSERT INTO Tables_to_Update
select '''+ #table +''', '''+ #column +''', count(*) from '+#table+ ' where '+ #column +' like ''%'+ #search +'%'''
EXEC(#SQL)
IF EXISTS (SELECT * FROM Tables_to_Update WHERE Table_name = #table)
BEGIN
SET #SQL = 'UPDATE '+ #table + ' SET '+ #column + ' = REPLACE('''+#column+''','''+#search+''','''+ #newvalue +''') WHERE '+ #column + ' like ''%'+#search+'%'''
--UPDATE HERE
IF (#Test = 1)
BEGIN
PRINT #SQL
END
ELSE
BEGIN
EXEC(#SQL)
END
END
UPDATE #columns SET Processed = 1 where COLUMN_NAME = #column
END
DROP TABLE #columns
UPDATE #tables SET Processed = 1 where table_name = #table
END
SELECT * FROM Tables_to_Update where recordsToUpdate > 0
END
The following will find and replace a string in every database (excluding system databases) on every table on the instance you are connected to:
Simply change 'Search String' to whatever you seek and 'Replace String' with whatever you want to replace it with.
--Getting all the databases and making a cursor
DECLARE db_cursor CURSOR FOR
SELECT name
FROM master.dbo.sysdatabases
WHERE name NOT IN ('master','model','msdb','tempdb') -- exclude these databases
DECLARE #databaseName nvarchar(1000)
--opening the cursor to move over the databases in this instance
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #databaseName
WHILE ##FETCH_STATUS = 0
BEGIN
PRINT #databaseName
--Setting up temp table for the results of our search
DECLARE #Results TABLE(TableName nvarchar(370), RealColumnName nvarchar(370), ColumnName nvarchar(370), ColumnValue nvarchar(3630))
SET NOCOUNT ON
DECLARE #SearchStr nvarchar(100), #ReplaceStr nvarchar(100), #SearchStr2 nvarchar(110)
SET #SearchStr = 'Search String'
SET #ReplaceStr = 'Replace String'
SET #SearchStr2 = QUOTENAME('%' + #SearchStr + '%','''')
DECLARE #TableName nvarchar(256), #ColumnName nvarchar(128)
SET #TableName = ''
--Looping over all the tables in the database
WHILE #TableName IS NOT NULL
BEGIN
DECLARE #SQL nvarchar(2000)
SET #ColumnName = ''
DECLARE #result NVARCHAR(256)
SET #SQL = 'USE ' + #databaseName + '
SELECT #result = MIN(QUOTENAME(TABLE_SCHEMA) + ''.'' + QUOTENAME(TABLE_NAME))
FROM [' + #databaseName + '].INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = ''BASE TABLE'' AND TABLE_CATALOG = ''' + #databaseName + '''
AND QUOTENAME(TABLE_SCHEMA) + ''.'' + QUOTENAME(TABLE_NAME) > ''' + #TableName + '''
AND OBJECTPROPERTY(
OBJECT_ID(
QUOTENAME(TABLE_SCHEMA) + ''.'' + QUOTENAME(TABLE_NAME)
), ''IsMSShipped''
) = 0'
EXEC master..sp_executesql #SQL, N'#result nvarchar(256) out', #result out
SET #TableName = #result
PRINT #TableName
WHILE (#TableName IS NOT NULL) AND (#ColumnName IS NOT NULL)
BEGIN
DECLARE #ColumnResult NVARCHAR(256)
SET #SQL = '
SELECT #ColumnResult = MIN(QUOTENAME(COLUMN_NAME))
FROM [' + #databaseName + '].INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = PARSENAME(''[' + #databaseName + '].' + #TableName + ''', 2)
AND TABLE_NAME = PARSENAME(''[' + #databaseName + '].' + #TableName + ''', 1)
AND DATA_TYPE IN (''char'', ''varchar'', ''nchar'', ''nvarchar'')
AND TABLE_CATALOG = ''' + #databaseName + '''
AND QUOTENAME(COLUMN_NAME) > ''' + #ColumnName + ''''
PRINT #SQL
EXEC master..sp_executesql #SQL, N'#ColumnResult nvarchar(256) out', #ColumnResult out
SET #ColumnName = #ColumnResult
PRINT #ColumnName
IF #ColumnName IS NOT NULL
BEGIN
INSERT INTO #Results
EXEC
(
'USE ' + #databaseName + '
SELECT ''' + #TableName + ''',''' + #ColumnName + ''',''' + #TableName + '.' + #ColumnName + ''', LEFT(' + #ColumnName + ', 3630)
FROM ' + #TableName + ' (NOLOCK) ' +
' WHERE ' + #ColumnName + ' LIKE ' + #SearchStr2
)
END
END
END
--Declaring another temporary table
DECLARE #time_to_update TABLE(TableName nvarchar(370), RealColumnName nvarchar(370))
INSERT INTO #time_to_update
SELECT TableName, RealColumnName FROM #Results GROUP BY TableName, RealColumnName
DECLARE #MyCursor CURSOR;
BEGIN
DECLARE #t nvarchar(370)
DECLARE #c nvarchar(370)
--Looping over the search results
SET #MyCursor = CURSOR FOR
SELECT TableName, RealColumnName FROM #time_to_update GROUP BY TableName, RealColumnName
--Getting my variables from the first item
OPEN #MyCursor
FETCH NEXT FROM #MyCursor
INTO #t, #c
WHILE ##FETCH_STATUS = 0
BEGIN
-- Updating the old values with the new value
DECLARE #sqlCommand varchar(1000)
SET #sqlCommand = '
USE ' + #databaseName + '
UPDATE [' + #databaseName + '].' + #t + ' SET ' + #c + ' = REPLACE(' + #c + ', ''' + #SearchStr + ''', ''' + #ReplaceStr + ''')
WHERE ' + #c + ' LIKE ''' + #SearchStr2 + ''''
PRINT #sqlCommand
BEGIN TRY
EXEC (#sqlCommand)
END TRY
BEGIN CATCH
PRINT ERROR_MESSAGE()
END CATCH
--Getting next row values
FETCH NEXT FROM #MyCursor
INTO #t, #c
END;
CLOSE #MyCursor ;
DEALLOCATE #MyCursor;
END;
DELETE FROM #time_to_update
DELETE FROM #Results
FETCH NEXT FROM db_cursor INTO #databaseName
END
CLOSE db_cursor
DEALLOCATE db_cursor
Note: this isn't ideal, nor is it optimized
Here is another answer, similar to above (and hopefully more readable/efficient), since I recently had a similar requirement and this is how I solved it.
CREATE OR ALTER PROCEDURE UPDATE_ALL_COLUMNS
#TableNameSearchFilter NVARCHAR(100),
#TableSchema NVARCHAR(100),
#TestValue NVARCHAR(100),
#NewValue NVARCHAR(100)
AS
BEGIN
DECLARE #NRCOLUMNS INT;
DECLARE #i INT = 0;
DECLARE #COLUMN NVARCHAR(100) = '';
DECLARE #SQL NVARCHAR(MAX) = '';
DECLARE #TableToUpdate NVARCHAR(256) = '';
DECLARE #insertingNULL BIT;
IF (#NewValue IS NULL) SET #insertingNULL = 1
ELSE SET #insertingNULL = 0;
WHILE #TableToUpdate IS NOT NULL
BEGIN
SELECT #TableToUpdate = MIN(TABLE_NAME)
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME LIKE #TableNameSearchFilter
AND TABLE_SCHEMA = #TableSchema
AND TABLE_NAME > #TableToUpdate;
WITH CTE1 AS
(
SELECT ROW_NUMBER() OVER (ORDER BY ORDINAL_POSITION) AS RN
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = #TableToUpdate
AND TABLE_SCHEMA = #TableSchema
AND (#insertingNULL = 0 OR (#insertingNULL = 1 AND IS_NULLABLE = 'YES'))
)
SELECT #i = MIN(RN), #NRCOLUMNS = MAX(RN) FROM CTE1;
WHILE (#i <= #NRCOLUMNS AND #TableToUpdate IS NOT NULL)
BEGIN
WITH CTE AS
(
SELECT *, ROW_NUMBER() OVER (ORDER BY ORDINAL_POSITION) AS RN
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = #TableToUpdate
AND TABLE_SCHEMA = #TableSchema
AND (#insertingNULL = 0 OR (#insertingNULL = 1 AND IS_NULLABLE = 'YES'))
)
SELECT #COLUMN = COLUMN_NAME
FROM CTE
WHERE RN = #i;
SET #SQL = #SQL +
N'UPDATE D SET ' + #COLUMN + N' = ' + ISNULL(N'''' + #NewValue + N'''', N'NULL')
+ N' FROM ' + #TableSchema + N'.' + #TableToUpdate + N' D WHERE CAST(D.' + #COLUMN + ' AS NVARCHAR) = ' + ISNULL(N'''' + #TestValue + N'''', N'NULL') + ';'
+ NCHAR(13) + NCHAR(10);
SET #i = #i + 1;
END;
END;
--PRINT SUBSTRING(#SQL, 1, 4000)
--PRINT SUBSTRING(#SQL, 4001, 8000)
--PRINT SUBSTRING(#SQL, 8001, 12000)
--PRINT SUBSTRING(#SQL, 12001, 16000)
--PRINT SUBSTRING(#SQL, 16001, 20000)
--PRINT SUBSTRING(#SQL, 20001, 24000)
EXEC (#SQL)
END
GO
As a usage example:
EXEC UPDATE_ALL_COLUMNS '%temp%', 'dbo', '', NULL
Parameters:
#TableNameSearchFilter - this will be used with the LIKE operator to find all the tables from your database whose names that match this value;
#TableSchema - the schema of the table (usually dbo)
#TestValue - the value to search for in ALL of the columns (and rows) of each found table;
#NewValue - the value to replace #TestValue with. Can also be NULL.
Explanation:
The EXEC statement will find ALL tables whose names contain the word 'temp', on the 'dbo' schema of your database, then search for the value '' (empty string) in ALL columns of ALL of the found tables, then replace this value with a NULL.
Obviously, if you have long(er) column/table names or the update value, make sure to update the limits on the parameters.
Make sure to first comment the last line (EXEC (#SQL)) and uncomment the lines with PRINT, just to get an idea for what the procedure does and how the final statements look like.
This is not going to work (most likely) if you want to search for the NULL value (i.e. to have #TestValue as NULL). Nevertheless, it can be easily changed to accomplish this as well, by replacing the equal sign from the WHERE clause (in the dynamic query) with IS NULL and removing the rest of the line, when #TestValue IS NULL.
Can be easily adapted to search for columns of only certain types (like VARCHAR etc).
The procedure accounts for inserting NULL values, and will only do so in NULLABLE columns.
I want to update some rows which be include some null fields.
How can I update these rows in SQL Server?
I am asking because a rows has got 180 fields. :)
Please help me.
You can use dynamic SQL to generate a script to run. The following will probably need tweaking for you to exclude columns that you don't want to update etc.
DECLARE #TableName nvarchar(500) = '[dbo].[T]'
DECLARE #DynSql nvarchar(max)
SELECT #DynSql = ISNULL(#DynSql+',','') + QUOTENAME(name) + '= ISNULL(' + QUOTENAME(name) + ',0)'
FROM sys.columns
WHERE object_id = OBJECT_ID(#TableName)
SET #DynSql = 'UPDATE ' + #TableName + 'SET ' + #DynSql
PRINT #DynSql
--EXEC(#DynSql)
I think I understand what you are asking. This will generate an update statement for each column in your table that will set it's value to 0 if it's value is null.
declare #tableName nvarchar(100)
declare #querys varchar(max)
set #querys = ''
set #tableName = 'YOUR TABLE NAME HERE'
select #querys = #querys + 'update ' + #tableName + ' set ' +
QUOTENAME(t.[name]) + '=0 where ' + QUOTENAME(t.[name]) + ' is null;'
from (SELECT [name] FROM syscolumns
WHERE id = (SELECT id
FROM sysobjects
WHERE type = 'U'
AND [NAME] = #tableName))t
select #querys
execute sp_executesql #sqlQuery
Well It is an old post, but I recently had this problem and wanted a dynamic SQL query using the above solution that performed the update depending on column types.
USE [YOUR DATABASE]
DECLARE #tableName nvarchar(100)
DECLARE #name varchar(50)
DECLARE #dtype varchar(50)
DECLARE #CMD NVARCHAR (200)
SET #tableName = [YOUR TABLE NAME]
DECLARE db_cursor CURSOR FOR
SELECT c.name, t.name AS Dtype
FROM sys.columns c
INNER JOIN sys.types t
ON t.system_type_id = c.system_type_id
WHERE c.[object_id] =
(SELECT [object_id] FROM sys.objects WHERE type = 'U' AND [NAME] = #tableName)
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO #name, #Dtype
WHILE ##FETCH_STATUS = 0 BEGIN
SET #CMD = 'UPDATE ' + #tableName + ' SET ' + quotename(#name) +' = ' +
(CASE
WHEN (#Dtype = 'bit') THEN '0'
WHEN (#Dtype = 'int') THEN '0'
WHEN (#Dtype = 'decimal') THEN '0'
WHEN (#Dtype = 'date') THEN '''1/1/1900'''
WHEN (#Dtype = 'datetime') THEN '''1/1/1900'''
WHEN (#Dtype = 'uniqueidentifier') THEN '00000000-0000-0000-0000-000000000000'
ELSE ''''''
END )
+ ' WHERE ' + quotename(#name) +' IS NULL'
PRINT #CMD
EXEC sp_executeSQL #cmd
FETCH NEXT FROM db_cursor INTO #name, #Dtype
END
CLOSE db_cursor
DEALLOCATE db_cursor
How do I select all the columns in a table that only contain NULL values for all the rows? I'm using MS SQL Server 2005. I'm trying to find out which columns are not used in the table so I can delete them.
Here is the sql 2005 or later version: Replace ADDR_Address with your tablename.
declare #col varchar(255), #cmd varchar(max)
DECLARE getinfo cursor for
SELECT c.name FROM sys.tables t JOIN sys.columns c ON t.Object_ID = c.Object_ID
WHERE t.Name = 'ADDR_Address'
OPEN getinfo
FETCH NEXT FROM getinfo into #col
WHILE ##FETCH_STATUS = 0
BEGIN
SELECT #cmd = 'IF NOT EXISTS (SELECT top 1 * FROM ADDR_Address WHERE [' + #col + '] IS NOT NULL) BEGIN print ''' + #col + ''' end'
EXEC(#cmd)
FETCH NEXT FROM getinfo into #col
END
CLOSE getinfo
DEALLOCATE getinfo
SELECT cols
FROM table
WHERE cols IS NULL
This should give you a list of all columns in the table "Person" that has only NULL-values. You will get the results as multiple result-sets, which are either empty or contains the name of a single column. You need to replace "Person" in two places to use it with another table.
DECLARE crs CURSOR LOCAL FAST_FORWARD FOR SELECT name FROM syscolumns WHERE id=OBJECT_ID('Person')
OPEN crs
DECLARE #name sysname
FETCH NEXT FROM crs INTO #name
WHILE ##FETCH_STATUS = 0
BEGIN
EXEC('SELECT ''' + #name + ''' WHERE NOT EXISTS (SELECT * FROM Person WHERE ' + #name + ' IS NOT NULL)')
FETCH NEXT FROM crs INTO #name
END
CLOSE crs
DEALLOCATE crs
Or did you want to just see if a column only has NULL values (and, thus, is probably unused)?
Further clarification of the question might help.
EDIT:
Ok.. here's some really rough code to get you going...
SET NOCOUNT ON
DECLARE #TableName Varchar(100)
SET #TableName='YourTableName'
CREATE TABLE #NullColumns (ColumnName Varchar(100), OnlyNulls BIT)
INSERT INTO #NullColumns (ColumnName, OnlyNulls) SELECT c.name, 0 FROM syscolumns c INNER JOIN sysobjects o ON c.id = o.id AND o.name = #TableName AND o.xtype = 'U'
DECLARE #DynamicSQL AS Nvarchar(2000)
DECLARE #ColumnName Varchar(100)
DECLARE #RC INT
SELECT TOP 1 #ColumnName = ColumnName FROM #NullColumns WHERE OnlyNulls=0
WHILE ##ROWCOUNT > 0
BEGIN
SET #RC=0
SET #DynamicSQL = 'SELECT TOP 1 1 As HasNonNulls FROM ' + #TableName + ' (nolock) WHERE ''' + #ColumnName + ''' IS NOT NULL'
EXEC sp_executesql #DynamicSQL
set #RC=##rowcount
IF #RC=1
BEGIN
SET #DynamicSQL = 'UPDATE #NullColumns SET OnlyNulls=1 WHERE ColumnName=''' + #ColumnName + ''''
EXEC sp_executesql #DynamicSQL
END
ELSE
BEGIN
SET #DynamicSQL = 'DELETE FROM #NullColumns WHERE ColumnName=''' + #ColumnName+ ''''
EXEC sp_executesql #DynamicSQL
END
SELECT TOP 1 #ColumnName = ColumnName FROM #NullColumns WHERE OnlyNulls=0
END
SELECT * FROM #NullColumns
DROP TABLE #NullColumns
SET NOCOUNT OFF
Yes, there are easier ways, but I have a meeting to go to right now. Good luck!
Here is an updated version of Bryan's query for 2008 and later. It uses INFORMATION_SCHEMA.COLUMNS, adds variables for the table schema and table name. The column data type was added to the output. Including the column data type helps when looking for a column of a particular data type. I didn't added the column widths or anything.
For output the RAISERROR ... WITH NOWAIT is used so text will display immediately instead of all at once (for the most part) at the end like PRINT does.
SET NOCOUNT ON;
DECLARE
#ColumnName sysname
,#DataType nvarchar(128)
,#cmd nvarchar(max)
,#TableSchema nvarchar(128) = 'dbo'
,#TableName sysname = 'TableName';
DECLARE getinfo CURSOR FOR
SELECT
c.COLUMN_NAME
,c.DATA_TYPE
FROM
INFORMATION_SCHEMA.COLUMNS AS c
WHERE
c.TABLE_SCHEMA = #TableSchema
AND c.TABLE_NAME = #TableName;
OPEN getinfo;
FETCH NEXT FROM getinfo INTO #ColumnName, #DataType;
WHILE ##FETCH_STATUS = 0
BEGIN
SET #cmd = N'IF NOT EXISTS (SELECT * FROM ' + #TableSchema + N'.' + #TableName + N' WHERE [' + #ColumnName + N'] IS NOT NULL) RAISERROR(''' + #ColumnName + N' (' + #DataType + N')'', 0, 0) WITH NOWAIT;';
EXECUTE (#cmd);
FETCH NEXT FROM getinfo INTO #ColumnName, #DataType;
END;
CLOSE getinfo;
DEALLOCATE getinfo;
You can do:
select
count(<columnName>)
from
<tableName>
If the count returns 0 that means that all rows in that column all NULL (or there is no rows at all in the table)
can be changed to
select
case(count(<columnName>)) when 0 then 'Nulls Only' else 'Some Values' end
from
<tableName>
If you want to automate it you can use system tables to iterate the column names in the table you are interested in
If you need to list all rows where all the column values are NULL, then i'd use the COLLATE function. This takes a list of values and returns the first non-null value. If you add all the column names to the list, then use IS NULL, you should get all the rows containing only nulls.
SELECT * FROM MyTable WHERE COLLATE(Col1, Col2, Col3, Col4......) IS NULL
You shouldn't really have any tables with ALL the columns null, as this means you don't have a primary key (not allowed to be null). Not having a primary key is something to be avoided; this breaks the first normal form.
Try this -
DECLARE #table VARCHAR(100) = 'dbo.table'
DECLARE #sql NVARCHAR(MAX) = ''
SELECT #sql = #sql + 'IF NOT EXISTS(SELECT 1 FROM ' + #table + ' WHERE ' + c.name + ' IS NOT NULL) PRINT ''' + c.name + ''''
FROM sys.objects o
JOIN sys.columns c ON o.[object_id] = c.[object_id]
WHERE o.[type] = 'U'
AND o.[object_id] = OBJECT_ID(#table)
AND c.is_nullable = 1
EXEC(#sql)
Not actually sure about 2005, but 2008 ate it:
USE [DATABASE_NAME] -- !
GO
DECLARE #SQL NVARCHAR(MAX)
DECLARE #TableName VARCHAR(255)
SET #TableName = 'TABLE_NAME' -- !
SELECT #SQL =
(
SELECT
CHAR(10)
+'DELETE FROM ['+t1.TABLE_CATALOG+'].['+t1.TABLE_SCHEMA+'].['+t1.TABLE_NAME+'] WHERE '
+(
SELECT
CASE t2.ORDINAL_POSITION
WHEN (SELECT MIN(t3.ORDINAL_POSITION) FROM INFORMATION_SCHEMA.COLUMNS t3 WHERE t3.TABLE_NAME=t2.TABLE_NAME) THEN ''
ELSE 'AND '
END
+'['+COLUMN_NAME+'] IS NULL' AS 'data()'
FROM INFORMATION_SCHEMA.COLUMNS t2 WHERE t2.TABLE_NAME=t1.TABLE_NAME FOR XML PATH('')
) AS 'data()'
FROM INFORMATION_SCHEMA.TABLES t1 WHERE t1.TABLE_NAME = #TableName FOR XML PATH('')
)
SELECT #SQL -- EXEC(#SQL)
Here I have created a script for any kind of SQL table. please copy this stored procedure and create this on your Environment and run this stored procedure with your Table.
exec [dbo].[SP_RemoveNullValues] 'Your_Table_Name'
stored procedure
GO
/****** Object: StoredProcedure [dbo].[SP_RemoveNullValues] Script Date: 09/09/2019 11:26:53 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- akila liyanaarachchi
Create procedure [dbo].[SP_RemoveNullValues](#PTableName Varchar(50) ) as
begin
DECLARE Cussor CURSOR FOR
SELECT COLUMN_NAME,TABLE_NAME,DATA_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = #PTableName
OPEN Cussor;
Declare #ColumnName Varchar(50)
Declare #TableName Varchar(50)
Declare #DataType Varchar(50)
Declare #Flage int
FETCH NEXT FROM Cussor INTO #ColumnName,#TableName,#DataType
WHILE ##FETCH_STATUS = 0
BEGIN
set #Flage=0
If(#DataType in('bigint','numeric','bit','smallint','decimal','smallmoney','int','tinyint','money','float','real'))
begin
set #Flage=1
end
If(#DataType in('date','atetimeoffset','datetime2','smalldatetime','datetime','time'))
begin
set #Flage=2
end
If(#DataType in('char','varchar','text','nchar','nvarchar','ntext'))
begin
set #Flage=3
end
If(#DataType in('binary','varbinary'))
begin
set #Flage=4
end
DECLARE #SQL VARCHAR(MAX)
if (#Flage in(1,4))
begin
SET #SQL =' update ['+#TableName+'] set ['+#ColumnName+']=0 where ['+#ColumnName+'] is null'
end
if (#Flage =3)
begin
SET #SQL =' update ['+#TableName+'] set ['+#ColumnName+'] = '''' where ['+#ColumnName+'] is null '
end
if (#Flage =2)
begin
SET #SQL =' update ['+#TableName+'] set ['+#ColumnName+'] ='+'''1901-01-01 00:00:00.000'''+' where ['+#ColumnName+'] is null '
end
EXEC(#SQL)
FETCH NEXT FROM Cussor INTO #ColumnName,#TableName,#DataType
END
CLOSE Cussor
DEALLOCATE Cussor
END
You'll have to loop over the set of columns and check each one. You should be able to get a list of all columns with a DESCRIBE table command.
Pseudo-code:
foreach $column ($cols) {
query("SELECT count(*) FROM table WHERE $column IS NOT NULL")
if($result is zero) {
# $column contains only null values"
push #onlyNullColumns, $column;
} else {
# $column contains non-null values
}
}
return #onlyNullColumns;
I know this seems a little counterintuitive but SQL does not provide a native method of selecting columns, only rows.
I would also recommend to search for fields which all have the same value, not just NULL.
That is, for each column in each table do the query:
SELECT COUNT(DISTINCT field) FROM tableName
and concentrate on those which return 1 as a result.
SELECT t.column_name
FROM user_tab_columns t
WHERE t.nullable = 'Y' AND t.table_name = 'table name here' AND t.num_distinct = 0;
An updated version of 'user2466387' version, with an additional small test which can improve performance, because it's useless to test non nullable columns:
AND IS_NULLABLE = 'YES'
The full code:
SET NOCOUNT ON;
DECLARE
#ColumnName sysname
,#DataType nvarchar(128)
,#cmd nvarchar(max)
,#TableSchema nvarchar(128) = 'dbo'
,#TableName sysname = 'TableName';
DECLARE getinfo CURSOR FOR
SELECT
c.COLUMN_NAME
,c.DATA_TYPE
FROM
INFORMATION_SCHEMA.COLUMNS AS c
WHERE
c.TABLE_SCHEMA = #TableSchema
AND c.TABLE_NAME = #TableName
AND IS_NULLABLE = 'YES';
OPEN getinfo;
FETCH NEXT FROM getinfo INTO #ColumnName, #DataType;
WHILE ##FETCH_STATUS = 0
BEGIN
SET #cmd = N'IF NOT EXISTS (SELECT * FROM ' + #TableSchema + N'.' + #TableName + N' WHERE [' + #ColumnName + N'] IS NOT NULL) RAISERROR(''' + #ColumnName + N' (' + #DataType + N')'', 0, 0) WITH NOWAIT;';
EXECUTE (#cmd);
FETCH NEXT FROM getinfo INTO #ColumnName, #DataType;
END;
CLOSE getinfo;
DEALLOCATE getinfo;
You might need to clarify a bit. What are you really trying to accomplish? If you really want to find out the column names that only contain null values, then you will have to loop through the scheama and do a dynamic query based on that.
I don't know which DBMS you are using, so I'll put some pseudo-code here.
for each col
begin
#cmd = 'if not exists (select * from tablename where ' + col + ' is not null begin print ' + col + ' end'
exec(#cmd)
end