Jonathan Porter Jonathan Porter - 1 year ago 113
SQL Question

T-SQL: How to find if a column exists in a list of tables

My goal is to get a list of tables from a stored procedure and then return the name of those tables along with their row count and if a

column exists in each table.

So far it almost works but this current code gives me back a few tables where it says
both exists and doesn't exist. I'm guessing the problem lies in that last select statement.

-- Create temporary table
[object_name] NVARCHAR(255) ,
[object_id] NVARCHAR(255),
[row_count] INT

-- Insert table names, object id and row count into temp table
[object_name] = SCHEMA_NAME(o.[schema_id]) + '.' + ,
FROM sys.dm_sql_referenced_entities('dbo.spMyStoredProcedure',
JOIN sys.objects o ON d.referenced_id = o.[object_id]
INNER JOIN sys.indexes AS i ON i.object_id = o.object_id
INNER JOIN sys.dm_db_partition_stats AS ddps ON i.object_id = ddps.object_id
AND i.index_id = ddps.index_id
WHERE o.[type] IN ( 'U', 'V' )
AND i.index_id < 2
AND o.is_ms_shipped = 0;

-- Join temp table to query that searches for a ModifiedDate column
SELECT DISTINCT t2.[object_name] AS 'TableName' ,
t2.[row_count] AS 'RowCount' ,
WHEN ='modifiedDate' THEN 'Yes'
WHEN <> 'modifiedDate' THEN 'No'
END AS 'ModifiedDateExists'
FROM sys.columns AS t1
RIGHT JOIN #TempTable AS t2 ON t1.object_id = t2.object_id;

-- Delete temp table
IF ( OBJECT_ID('mydbhere..#TempTable') IS NOT NULL )

Answer Source

The problem is the sys.columns will contain multiple records for 1 object (table) (one for each column). You need a 1-1 relationship there. The distinct your using is hiding the fact that you'd have ALOT more rows (1 for each field infact.) So you need to ensure only 1 record is returned from the join between sys.columns and #TempTable. This can be done by only searching for modifiedDate and allowing the existing of a NULL on your right join to mean that it doesn't exit.

SELECT  t2.[object_name] AS 'TableName' 
     ,  t2.[row_count] AS 'RowCount' 
     , case when is not null then 'YES' else 'No' as 'ModifiedDateExists'
FROM sys.columns AS t1
RIGHT JOIN #TempTable AS t2 
  ON t1.object_id = t2.object_id
 and ='modifiedDate'

Since SQL server will prevent the same named object (column/filed) from being in a table, simply limit to just that column; all other records would result in a Null, and then in our case statement we can say yes or no.

All the tables in #tempTable will be returned but only 1 column.

General rule of thumb is to avoid Distinct unless you REALLY Mean it as it generally is just hiding a problem on a join, limit or something.

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