Search table columns for values over a certain length - sql

Question

So I have a database with many tables that have a column that contains a GL Account value (for financial purposes). The column name varies by table (i.e. in one table the column is called "gldebitaccount" and in another table it's called "glcreditaccount"). I was able to find all combinations of table / column pairs using the following query:
SELECT c.name AS ColName, t.name AS TableName
FROM sys.columns c
JOIN sys.tables t ON c.object_id = t.object_id
WHERE c.name LIKE '%gl%acc%'
This query returns close to 100 pairs of tables/columns. I am trying to find any value in any of those table/column pairs that exceeds 25 chars in length. For an individual table/column, I'd typically use:
SELECT *
FROM tableName
WHERE LEN(columnName)>25
I want to avoid having to run that query 100 times with each pair. Is there any way I can do a "for each" (which I know is frowned upon in SQL since everything should be set-based). I've done sub-SELECT statements before, but not any that involved change the table in the FROM clause. Any ideas or help would be greatly appreciated!
Thanks in advance!

Answer 1

As the previous answer, the solution will need dynamic SQL. Here is a way that uses both dynamic SQL and cursors, and you can expect slow performance, so use at your own risk:
DECLARE #TableName NVARCHAR(128), #ColumnName NVARCHAR(128)
DECLARE #Query NVARCHAR(4000)
DECLARE CC CURSOR LOCAL FAST_FORWARD FOR
SELECT QUOTENAME(t.name), QUOTENAME(c.name)
FROM sys.columns c
INNER JOIN sys.tables t
ON c.object_id = t.object_id
WHERE c.collation_name IS NOT NULL
AND c.max_length > 25 AND c.name LIKE '%gl%acc%';
CREATE TABLE #Results(TableName NVARCHAR(128), ColumnName NVARCHAR(128));
OPEN CC
FETCH NEXT FROM CC INTO #TableName, #ColumnName
WHILE ##FETCH_STATUS = 0
BEGIN
SET #Query = 'IF EXISTS(SELECT 1 FROM '+#TableName+'
WHERE LEN('+#ColumnName+') > 25)
INSERT INTO #Results
VALUES(#TableName,#ColumnName)'
EXEC sp_executesql #Query,
N'#TableName NVARCHAR(128),#ColumnName NVARCHAR(128)',
#TableName,
#ColumnName;
FETCH NEXT FROM CC INTO #TableName, #ColumnName
END
CLOSE CC
DEALLOCATE CC
SELECT *
FROM #Results

Answer 2

Here's an option without cursors that also doesn't add XML overhead. Note that it also protects you from potential type conflicts (e.g. try the others in a database with hierarchyid columns, like AdventureWorks), from table or column names with apostrophes, and from table names that exist in more than one schema.
DECLARE #sql NVARCHAR(MAX) = N'';
CREATE TABLE #Results
(
SchemaName NVARCHAR(128), TableName NVARCHAR(128), ColumnName NVARCHAR(128)
);
SELECT #sql += N'INSERT #Results SELECT '''
+ REPLACE(s.name,'''','''''') + ''','''
+ REPLACE(t.name,'''','''''') + ''','''
+ REPLACE(c.name,'''','''''') + '''
WHERE EXISTS (SELECT 1 FROM ' + QUOTENAME(s.name)
+ '.' + QUOTENAME(t.name) + ' WHERE
LEN(' + QUOTENAME(c.name) + ') > 25);
'
FROM sys.columns AS c
INNER JOIN sys.tables AS t
ON c.[object_id] = t.[object_id]
INNER JOIN sys.schemas AS s
ON t.[schema_id] = s.[schema_id]
WHERE
(
c.system_type_id IN (35,99) -- text,ntext
OR (c.system_type_id IN (167,231) -- varchar,nvarchar, could be max
AND c.max_length > 25 OR c.max_length = -1)
OR (c.system_type_id IN (175,239) -- char, nchar
AND c.max_length > 25)
)
AND c.name LIKE N'%gl%acc%';
EXEC sp_executesql #sql;
SELECT SchemaName, TableName, ColumnName FROM #Results;

Answer 3

Yet another solution with dynamic SQL.
But now without cursors. It uses FOR XML statement and should be much faster.
DECLARE #sqlstatement VARCHAR(MAX);
SET #sqlstatement =
REPLACE (
STUFF ( (
SELECT 'UNION ALL SELECT ''' + t.name + ''' as TableName, '''
+ c.name + ''' AS ColumnName, '
+ c.name + ' AS Value FROM '
+ t.name + ' WHERE LEN (' + c.name + ') ' + CHAR(62) + ' 25'
FROM sys.columns c
INNER JOIN sys.tables t ON c.object_id = t.object_id
WHERE c.name LIKE '%gl%acc%'
FOR XML PATH('')
), 1, 10, '')
, '>', '>')
EXEC (#sqlstatement)
You may want to add extra filter for columns by their type and max_length:
INNER JOIN sys.types ty ON c.system_type_id = ty.system_type_id
AND (
ty.name IN ('text', 'ntext')
OR (
ty.name IN ('varchar', 'char', 'nvarchar', 'nchar')
AND (c.max_length > 25 OR c.max_length = -1)
)

Answer 4

You will need to create dynamic SQL because you cannot dynamically specify the source table. You could do this using a cursor, or write a select statement that makes a row for each statement you need to run. This shows how to do it with a cursor. You problem looks like an acceptable usage for a cursor:
DECLARE #ColName VARCHAR(MAX);
DECLARE #TableName VARCHAR(MAX);
DECLARE #SomeSQL VARCHAR(MAX);
DECLARE db_cursor CURSOR FOR
SELECT c.name AS ColName, t.name AS TableName
FROM sys.columns c
JOIN sys.tables t ON c.object_id = t.object_id
WHERE c.name LIKE '%gl%acc%'
OPEN db_cursor;
FETCH NEXT FROM db_cursor INTO #ColName, #TableName;
WHILE ##FETCH_STATUS = 0
BEGIN
-- you need to make dynamic SQL
SELECT #SomeSQL = 'SELECT * FROM ' + #TableName + ' WHERE LEN(' + #ColName + ') > 25;'
PRINT(#SomeSQL + CHAR(10));
-- you could execute it directly if you wish.
--EXEC (#SomeSQL);
FETCH NEXT FROM db_cursor INTO #ColName, #TableName;
END
CLOSE db_cursor;
DEALLOCATE db_cursor;

Answer 5

I wasn't sure if you needed to do anything with the results, but this will return the records that meet the criteria you posted in your question
Declare #TableName sysname
Declare #ColName sysname
Declare #dynamic_SQL varchar(MAX)
Declare some_cursor CURSOR FOR
SELECT c.name AS ColName, t.name AS TableName
FROM sys.columns c
JOIN sys.tables t ON c.object_id = t.object_id
WHERE c.name LIKE '%gl%acc%'
OPEN some_cursor
FETCH NEXT FROM some_cursor INTO #ColName, #TableName
WHILE ##FETCH_STATUS = 0
Begin
select #dynamic_SQL = '
Select *
From ' + #TableName + '
Where LEN('+ #ColName +') > 25
'
exec (#dynamic_SQL)
FETCH NEXT FROM some_cursor INTO #ColName, #TableName
End
CLOSE some_cursor
DEALLOCATE some_cursor