I want to delete the ABCDEF column from all tables of my database. I am trying this code:
declare #SQL nvarchar(max)
SELECT
#SQL = STUFF((SELECT ' DROP column ' + quotename(TABLE_SCHEMA) + '.' + quotename(table_NAME ) +'.ABCDEF;'
FROM
information_schema.columns
FOR XML PATH('')),1,2,'')
PRINT #SQL
EXECUTE (#SQL)
But I am getting an error
incorrect syntax near column
How to do this?
You can use an undocumented feature of SQL Server sys.sp_msforeachtable. The below script will basically iterate for all the tables in database and alter them if required.
select '[dbo].['+tab.name+']' name into #table from
sys.tables tab join sys.columns col on tab.object_id = col.object_id and col.name = 'ABCDEF'
exec sys.sp_msforeachtable 'if exists (select 1 from #table where name = ''?'')
alter table ? drop column [ABCDEF]'
That's not the right way to drop a column from a table. It should be
ALTER TABLE table_name DROP COLUMN column_name
Build your dynamic query something like this:
DECLARE #sql NVARCHAR(max)=''
SELECT #SQL += 'Alter table ' + Quotename(table_catalog)
+ '.' + Quotename(table_schema) + '.'
+ Quotename(TABLE_NAME) + ' DROP column '
+ Quotename(column_name) + ';'
FROM information_schema.columns where COLUMN_NAME = 'abcd' -- Here alone mention
--the Column to be removed
EXEC Sp_executesql #sql
While dropping the columns from multiple tables, I faced following default constraints error.
The object 'DF_TableName_ColumnName' is dependent on column 'ColumnName'.
To resolve this, I have to drop all those constraints first, by using following query
DECLARE #sql NVARCHAR(max)=''
SELECT #SQL += 'Alter table ' + Quotename(tbl.name) + ' DROP constraint ' + Quotename(cons.name) + ';'
FROM SYS.DEFAULT_CONSTRAINTS cons
JOIN SYS.COLUMNS col ON col.default_object_id = cons.object_id
JOIN SYS.TABLES tbl ON tbl.object_id = col.object_id
WHERE col.[name] IN ('Column1','Column2')
--PRINT #sql
EXEC Sp_executesql #sql
After that, I dropped all those columns by using the answer above.
DECLARE #sql NVARCHAR(max)=''
SELECT #SQL += 'Alter table ' + Quotename(table_catalog)+ '.' + Quotename(table_schema) + '.'+ Quotename(TABLE_NAME)
+ ' DROP column ' + Quotename(column_name) + ';'
FROM information_schema.columns where COLUMN_NAME IN ('Column1','Column2')
--PRINT #sql
EXEC Sp_executesql #sql
I posted here in case someone find the same issue.
Happy Coding!
Related
I am trying to get all the table names and the values present in a particular column if the column is present in the database. For the tables without the column ignore those.
For example: Find all the table name and values from a column 'last_refresh_date' in a database for all the tables with last_refresh_date column.
The code I tried is:
EXEC sp_MSforeachtable 'SELECT distinct ''?'' TableName, last_refresh_date FROM ?'
I get an error as some of the tables doesn't have the column name 'last_refresh_date' in it.
Thanks for the help in advance
I'm going to assume you are using a recent version of SQL Server, and thus have access to STRING_AGG, if not you'll need to use the "old" FOR XML PATH method.
Anyway, you achieve this with a little bit of dynamic SQL, and UNION ALL. I assume you want the table and schema names as well:
DECLARE #SQL nvarchar(MAX),
#ColumnName sysname = N'YourColumnName',
#CRLF nchar(2) = CHAR(13) + CHAR(10);
DECLARE #Delimiter nvarchar(30) = #CRLF + N'UNION ALL' + #CRLF
SET #SQL = (SELECT STRING_AGG(N'SELECT N' + QUOTENAME(s.[name],'''') + N' AS SchemaName, N' + QUOTENAME(t.[name],'''') + N' AS TableName, ' + QUOTENAME(c.[name]) + N' FROM ' + QUOTENAME(s.[name]) + N'.' + QUOTENAME(t.[name]), #Delimiter) WITHIN GROUP (ORDER BY t.object_id)
FROM sys.schemas s
JOIN sys.tables t ON s.schema_id = t.schema_id
JOIN sys.columns c ON t.object_id = c.object_id
WHERE c.[name] = #ColumnName)
EXEC sys.sp_executesql #SQL;
I am trying to set a default value to a column(Inserted_time), but first i need to check if the column exists in the tables. If the column doesn't exist, I need to add that column and give it a default value.
I am working with Sql Server Management Studio.
So far I have written this code:
IF EXISTS ( select TABLE_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_CATALOG = 'DB_COPY' and COLUMN_NAME = 'Inserted_Time')
begin
ALTER TABLE table_name ADD CONSTRAINT [Inserted_Time_Def] SET DEFAULT (sysdatetimeoffset()) FOR [Inserted_Time]
end
else
ALTER TABLE table_name ADD COLUMN [Inserted_Time] CONSTRAINT [Inserted_Time_Def] DEFAULT (sysdatetimeoffset()) WITH VALUES
Once I retrieve the tables that has the column, I need to add that table_name to the Alter command. But I am not able to do that. Can someone please tell me how to use the table_names retrieved from select statement in the alter statement?
First, you want to put all the table names in a temporary table so you can loop through it.
After, you can use a cursor to execute a command for each table name.
In my example, I only printed the command I wanted to execute. That way you can be sure the code will do what you want first.
Example :
select TABLE_NAME As TableName INTO #TablesList from INFORMATION_SCHEMA.COLUMNS where TABLE_CATALOG = 'DB_COPY' and COLUMN_NAME = 'Inserted_Time'
DECLARE #TablesCursor as CURSOR;
DECLARE #TableName as NVARCHAR(max);
DECLARE #CommandToExecute as NVARCHAR(max);
SET #TablesCursor = CURSOR FOR SELECT TableName FROM #TablesList;
OPEN #TablesCursor;
FETCH NEXT FROM #TablesCursor INTO #TableName;
WHILE ##FETCH_STATUS = 0
BEGIN
SET #CommandToExecute = 'ALTER TABLE ' + #TableName + ' WHAT YOU WANNA DO '
PRINT #CommandToExecute
--EXEC(#CommandToExecute)
FETCH NEXT FROM #TablesCursor INTO #TableName;
END
CLOSE #TablesCursor;
DEALLOCATE #TablesCursor;
Assuming that every table is in a different schema, then you could do something like this:
DECLARE #SQL nvarchar(MAX);
SET #SQL = STUFF((SELECT NCHAR(13) + NCHAR(10) +
CASE WHEN EXISTS (SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS C
WHERE T.TABLE_SCHEMA = C.TABLE_SCHEMA
AND T.TABLE_NAME = C.TABLE_SCHEMA
AND C.COLUMN_NAME = N'Inserted_Time') THEN N'ALTER TABLE ' + QUOTENAME(T.TABLE_SCHEMA) + N'.' + QUOTENAME(T.TABLE_NAME) + N' ADD CONSTRAINT [Inserted_Time_Def] DEFAULT (sysdatetimeoffset()) FOR [Inserted_Time];'
ELSE N'ALTER TABLE ' + QUOTENAME(T.TABLE_SCHEMA) + N'.' + QUOTENAME(T.TABLE_NAME) + N' ADD COLUMN [Inserted_Time] CONSTRAINT [Inserted_Time_Def] DEFAULT (sysdatetimeoffset());'
END
FROM INFORMATION_SCHEMA.TABLES T
WHERE T.TABLE_CATALOG = N'DB_COPY'
FOR XML PATH(N''),TYPE).value('.','nvarchar(MAX)'),1,2,N'');
PRINT #SQL; --Your best friend. If more than 4,000 characters, use SELECT
EXECUTE sp_executesql #SQL;
This will very likely hugely out perform a CURSOR solution if you have a large number of schemas.
I've too many columns with DECIMAL(A,B). Some of them have column default, some of them nullable, etc.
Instead of using:
ALTER TABLE TABLE_NAME ALTER COLUMN COLUMN_NAME DECIMAL(A,C)
Is there method that simply updates the SCALE of the DECIMAL?
You can try with modify keyword
ALTER TABLE "table_name" MODIFY "column_name" "New Data Type";
Here is one way
DECLARE #sql VARCHAR(max)= ''
SET #sql = (SELECT 'ALTER TABLE TABLE_NAME ALTER COLUMN ' + COLUMN_NAME + ' DECIMAL(A,C);'
FROM information_schema.columns
WHERE table_name = 'TABLE_NAME'
AND data_type = 'DECIMAL'
AND NUMERIC_SCALE = --B
--add relevant filters
FOR xml path(''))
--print #sql
EXEC (#sql)
Don't forget to replace A and C with proper Precision and Scale
Use can achieve it by executing a dynamic SQL query. Use stuff function to concatenate each alter statement and retrieve the column names and other details from information_schema.columns. Create an other variable to hold the new numeric_scale value and take numeric_precision from the information_schema.columns itself.
Query
declare #sql as varchar(max);
declare #i as int = 3; -- change accordingly
select #sql = stuff((
select 'alter table ' + [table_name]
+ ' alter column ' + [column_name] + ' decimal('
+ cast([numeric_precision] as varchar(100)) + ',' + cast(#i as varchar(100)) + ');'
from information_schema.columns
where table_name = 'your_table_name'
and data_type = 'decimal'
for xml path('')
)
, 1, 0, ''
);
exec(#sql);
I want to select phone numbers from all tables in my databese and names of these tables too. I write a query that shows me all phone_numbers but I dont't know how to select table name to each phone number. This is my query:
DECLARE #SQL AS VarChar(MAX)
SET #SQL = ''
SELECT #SQL = #SQL + 'SELECT phone_number FROM ' + TABLE_SCHEMA + '.[' + TABLE_NAME + ']' + CHAR(13)
FROM INFORMATION_SCHEMA.TABLES where table_name in (select table_name
from information_schema.columns
where column_name = 'phone_number'
)
You can simply add the table name as a constant to the SELECT clause. But, I presume you're going to want to run this query, which means you have a few more things to change:
You're probably going to want sp_executesql, which requires a Unicode variable. So, you need to DECLARE #SQL NVARCHAR(MAX).
Do you want one result set or multiple result sets? I'm guessing you want all the results in one result set, which means you're going to want to use UNION ALL between the parts of the query.
So, try something like this:
DECLARE #sql NVARCHAR(MAX)
SET #sql = N'SELECT '''' AS table_name, '''' AS phone_number FROM [dbo].[SomeTable] WHERE 1 = 0'
DECLARE #table_name SYSNAME
DECLARE cur CURSOR LOCAL FAST_FORWARD FOR
SELECT table_name
FROM INFORMATION_SCHEMA.columns
WHERE column_name = 'phone_number'
OPEN cur
FETCH NEXT FROM cur INTO #table_name
WHILE ##FETCH_STATUS = 0
BEGIN
SET #sql = #sql + N' UNION ALL SELECT ''' + #table_name + N''', phone_number FROM [' + #table_name + N']'
FETCH NEXT FROM cur INTO #table_name
END
CLOSE cur
DEALLOCATE cur
EXEC sp_executesql #sql
When I used [dbo].[SomeTable], just use some table that you know exists. You would also need to modify the query if you want fully-qualified table names, but the above should get you started.
Another solution without CURSOR. You could combine each query with UNION like this.
--SELECT DISTINCT phone_number FROM dbo.Course c
DECLARE #sql nvarchar(max) = ''
SELECT #sql = #sql + N' SELECT DISTINCT phone_number, '''+ s.name + '.' + t.name + ''' AS TableName
FROM '+ s.name + '.' + t.name + Char(13) + ' UNION' + char(13)
FROM sys.tables t
INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
INNER JOIN sys.columns c ON c.object_id = t.object_id
WHERE c.name ='phone_number'
IF(#sql != '')
BEGIN
SET #sql = LEFT(#sql,len(#sql) - 6) -- remove last UNION
PRINT #sql
-- execute sql
EXEC sp_executesql #sql
END
I also add column TableName: Table of phone_number
If you want TableName if the first column then change it
SELECT #sql = #sql + N' SELECT DISTINCT '''+ s.name + '.' + t.name + ''' AS TableName, phone_number
FROM '+ s.name + '.' + t.name + Char(13) + ' UNION' + char(13)
I have some bulk views to create for an entire database.
To create a view the general syntax is as follows:
CREATE VIEW [TABLE_NAME]
AS
SELECT [COLUMN1], [COLUMN2], [COLUMN3], [COLUMN4]
FROM [TABLE_NAME]
WITH CHECK OPTION;
I would like to set the column names in the script above by querying the column names ([COLULMN1], [COLUMN2], etc) from INFORMATION_SCHEMA.COLUMNS.
Is there a way to achieve this by table name?
COALESCE is your friend good programmer. What you want to do is get a csv list of COLUMNS. Then using dynamic sql you can auto generate the rest of the code.
declare #columns AS VARCHAR(MAX)
SELECT #COLUMNS = NULL
select #COLUMNS = coalesce(#columns+',','')+c.name from syscolumns as c
inner join sysobjects as o on c.id = o.id
WHERE O.NAME = 'change me to your table name'
SELECT #COLUMNS
SELECT ' CREATE VIEW ' + 'COOL VIEW NAME' + ' AS ' +
' SELECT ' + #COLUMNS +
' FROM '+ ' change me to your table name '+
' WITH CHECK OPTION;'
EDIT
I purposely didn't declare the view anywhere. If you want to declare the view just execute the scripts like so. BUT YOU SHOULD NEVER just execute code on your servers without reading it all I purposely excluded the execution part as I think it is bad judgement just to cut and paste code and execute it without understanding/testing.
DECLARE #sql varchar(max)
SELECT #sql = ' CREATE VIEW ' + 'COOL VIEW NAME' + ' AS ' +
' SELECT ' + #COLUMNS +
' FROM '+ ' change me to your table name '+
' WITH CHECK OPTION;'
EXEC(#sql);
Here's one option... replace "MyTableName" with the table name you want, or wrap it in a cursor that reads TABLE_NAME from INFORMATION_SCHEMA.VIEWS into #tableName:
DECLARE #tableName sysname;
DECLARE #sql nvarchar(max);
DECLARE #columnList nvarchar(max);
SELECT #tableName = 'MyTableName';
SELECT #columnList = '';
SELECT #columnList += CASE WHEN LEN(#columnList) = 0 THEN '' ELSE ', ' END + COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = #tableName ORDER BY ORDINAL_POSITION;
SELECT #sql = 'CREATE VIEW [TABLE_NAME] AS
SELECT ' + #columnList + '
FROM [' + #tableName + ']
WITH CHECK OPTION;'
PRINT #sql
EXEC(#sql);