How to execute query (update) stored in table (query)? - sql-server

Question

I'm trying to execute the result of this query.
SELECT 'UPDATE [' + TABLE_SCHEMA + '].[' + TABLE_NAME + '] ' + 'SET [' + COLUMN_NAME + '] = RTRIM(LTRIM(SUBSTRING ([' + COLUMN_NAME + '], 2 , LEN ([' + COLUMN_NAME + ']) - 2) )) WHERE LEFT([' + COLUMN_NAME + '], 1) = ' + '''"''' + ' AND RIGHT([' + COLUMN_NAME + '], 1) = ' + '''"'''
FROM INFORMATION_SCHEMA.COLUMNS
WHERE DATA_TYPE IN ('varchar', 'nvarchar')
ORDER BY TABLE_NAME, COLUMN_NAME
It return more one row. For example:
UPDATE [dbo].[ACCDB] SET [ACODI] = RTRIM(LTRIM(SUBSTRING ([ACODI], 2 , LEN ([ACODI]) - 2) )) WHERE LEFT([ACODI], 1) = '"' AND RIGHT([ACODI], 1) = '"'
UPDATE [dbo].[ANAGP] SET [CDIVA] = RTRIM(LTRIM(SUBSTRING ([CDIVA], 2 , LEN ([CDIVA]) - 2) )) WHERE LEFT([CDIVA], 1) = '"' AND RIGHT([CDIVA], 1) = '"'
Now, how I execute this row programmatically? Without I write every row in stored procedure?
Thanks, I wait answer.

Answer 1

What you're trying to do here is dynamic SQL; building your queries on the fly. There are a number of ways to do that. Since you're building multiple statements, you need to be able to execute them one at a time. McNets's answer suggests using a cursor, which is one common way to do what you're after. Another way is to break up your statements with a loop, then execute them one after the other.
The code below gets a list of table names first, defining how many statements we may end up with. Mostly, the ID column is what we care about here. Then there's a WHILE loop to run your query once for each table, with a check to make sure we need to execute the statement for that table.
DECLARE #SqlText NVARCHAR(2000) --Variable to hold your query
,#Counter INT --Counter to keep track of where we are in the loop
,#EndLoop INT; --Value to stop the loop
DECLARE #TblList TABLE (
[ID] INT IDENTITY(1,1)
,[Schema] NVARCHAR(128)
,[Table] NVARCHAR(128));
INSERT INTO #TblList ([Schema],[Table])
SELECT
TABLE_SCHEMA
,TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES;
SELECT #Counter = MIN([ID]), #EndLoop = MAX([ID])
FROM #TblList;
WHILE #Counter <= #EndLoop
BEGIN
IF EXISTS ( --If there are no character columns, skip the table
SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS AS col JOIN #TblList AS tbl
ON tbl.[Schema] = col.TABLE_SCHEMA
AND tbl.[Table] = col.TABLE_NAME
AND tbl.[ID] = #Counter
AND col.DATA_TYPE IN ('varchar', 'nvarchar')
)
BEGIN
--Construct the query
SELECT #SqlText = CAST('UPDATE [' + col.TABLE_SCHEMA + '].[' + col.TABLE_NAME + '] ' + 'SET [' + col.COLUMN_NAME + '] = RTRIM(LTRIM(SUBSTRING ([' + col.COLUMN_NAME + '], 2 , LEN ([' + col.COLUMN_NAME + ']) - 2) )) WHERE LEFT([' + col.COLUMN_NAME + '], 1) = ' + '''"''' + ' AND RIGHT([' + col.COLUMN_NAME + '], 1) = ' + '''"''' AS NVARCHAR(2000))
FROM INFORMATION_SCHEMA.COLUMNS AS col
JOIN #TblList AS tbl
ON tbl.[Schema] = col.TABLE_SCHEMA
AND tbl.[Table] = col.TABLE_NAME
AND tbl.[ID] = #Counter
AND col.DATA_TYPE IN ('varchar', 'nvarchar');
--Run the query
EXEC sp_executesql #SQL;
END
--Increment the counter to move through the table list
SET #Counter = #Counter + 1;
END

Answer 2

I'd suggest to use a CURSOR to execute it line by line.
Have a look at one o my answers on dba.stackexchange.com for a similar question.
Restore all IDENTITY seeds (out of sync since database restore)

Answer 3

DECLARE #c_Statement VARCHAR(MAX)
DECLARE StatementCursor CURSOR FOR
SELECT 'UPDATE [' + TABLE_SCHEMA + '].[' + TABLE_NAME + '] ' + 'SET [' + COLUMN_NAME + '] = RTRIM(LTRIM(SUBSTRING ([' + COLUMN_NAME + '], 2 , LEN ([' + COLUMN_NAME + ']) - 2) )) WHERE LEFT([' + COLUMN_NAME + '], 1) = ' + '''"''' + ' AND RIGHT([' + COLUMN_NAME + '], 1) = ' + '''"'''
FROM INFORMATION_SCHEMA.COLUMNS
WHERE DATA_TYPE IN ('varchar', 'nvarchar')
ORDER BY TABLE_NAME, COLUMN_NAME
OPEN StatementCursor
FETCH NEXT FROM StatementCursor INTO #c_Statement
WHILE ##FETCH_STATUS = 0
BEGIN
EXEC(#c_Statement)
FETCH NEXT FROM StatementCursor INTO #c_Statement
END
CLOSE StatementCursor
DEALLOCATE StatementCursor
You may wanna check QUOTENAME() function to wrap object names in quotes instead of hard-coding them in the expression. You also need to check for errors (TRY/CATCH) and validate your user permissions to update the resulting rows.
If you have multiple databases, INFORMATION_SCHEMA.COLUMNS will only list the ones from the current connection.