ms sql server how to check table has “id” column and count rows if "id" exist - sql

Question

There are too many tables in my SQL Server db. Most of them have an 'id' column, but some do not. I want to know which table(s) doesn't have the 'id' column and to count the rows where id=null if an 'id' column exists. The query results may look like this:
TABLE_NAME | HAS_ID | ID_NULL_COUNT | ID_NOT_NULL_COUNT
table1 | false | 0 | 0
table2 | true | 10 | 100
How do I write this query?

Answer 1

Building query:
WITH cte AS (
SELECT t.*, has_id = CASE WHEN COLUMN_NAME = 'ID' THEN 'true' ELSE 'false' END
FROM INFORMATION_SCHEMA.TABLES t
OUTER APPLY (SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS c
WHERE t.TABLE_NAME = c.TABLE_NAME
AND t.[TABLE_SCHEMA] = c.[TABLE_SCHEMA]
AND c.COLUMN_NAME = 'id') s
WHERE t.TABLE_SCHEMA IN (...)
)
SELECT
query_to_run = REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
'SELECT tab_name = ''<tab_name>'',
has_id = ''<has_id>'',
id_null_count = <id_null_count>,
id_not_null_count = <id_not_null_count>
FROM <schema_name>.<tab_name>'
,'<tab_name>', TABLE_NAME)
,'<schema_name>', TABLE_SCHEMA)
,'<has_id>', has_id)
,'<id_null_count>', CASE WHEN has_id = 'false' THEN '0' ELSE 'SUM(CASE WHEN id IS NULL THEN 1 END)' END)
,'<id_not_null_count>', CASE WHEN has_id = 'false' THEN '0' ELSE 'COUNT(id)' END)
FROM cte;
Copy the output and execute in separate window. UNION ALL could be added to get single resultset.
db<>fiddle demo

Answer 2

This might be useful for you... lists out the row count for all tables that have an "id" column. It filters out tables that start with "sys" because those are mostly internal tables. If you have a table that starts with "sys", you'll probably want to delete that part of the WHERE clause.
SELECT DISTINCT OBJECT_NAME(r.[object_id]) AS [TableName], [row_count] AS [RowCount]
FROM sys.dm_db_partition_stats r
WHERE index_id = 1
AND EXISTS (SELECT 1 FROM sys.columns c WHERE c.[object_id] = r.[object_id] AND c.[name] = N'id')
AND OBJECT_NAME(r.[object_id]) NOT LIKE 'sys%'
ORDER BY [TableName]
Note you can change the "c.[name] = N'id'" to be any column name, or even change the "=" to "<>" to find only tables without an id column

Answer 3

pmbAustin answers how to list all tables without "ID" column.
To know how many rows in each table, SQL Server has a built-in report for you.
Right click the database in SSMS, click "Reports", "Standard Reports" then "Disk Usage by Table"
You now know how many rows in each table, and from pmbAustin's answer you know how which tables do and do not have "ID" columns. with a simple Vlookup in Excel you can combine these two datasets to arrive at any answer you wish.

Answer 4

This will give you the info about which tables have or not have column named "ID":
SELECT Table_Name
, case when column_name not like '%ID%' then 'false'
else 'true'
end as HAS_ID
FROM INFORMATION_SCHEMA.COLUMNS;
Here is a small demo
And here is one way that you can use to select all the tables that have columns named ID and if this columns are null or not:
CREATE TABLE #AllIDSNullable (TABLE_NAME NVARCHAR(256) NOT NULL
, HAS_ID VARCHAR(10)
, ID_NULL_COUNT INT DEFAULT 0
, ID_NOT_NULL_COUNT INT DEFAULT 0);
DECLARE CT CURSOR FOR
SELECT Table_Name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE column_name = 'ID';
DECLARE #name NVARCHAR(MAX), #SQL NVARCHAR(MAX);
OPEN CT; FETCH NEXT FROM CT INTO #name;
WHILE ##FETCH_STATUS=0 BEGIN
SET #SQL = 'INSERT #AllIDSNullable (TABLE_NAME , HAS_ID) SELECT Table_Name, case when column_name not like ''%ID%'' then ''false'' else ''true'' end FROM INFORMATION_SCHEMA.COLUMNS;';
EXEC (#SQL);
SET #SQL = 'UPDATE #AllIDSNullable SET ID_NULL_COUNT = (SELECT COUNT(*) FROM ['+#name+'] WHERE ID IS NULL), ID_NOT_NULL_COUNT = (SELECT COUNT(*) FROM ['+#name+'] WHERE ID IS NOT NULL) WHERE TABLE_NAME='''+#name+''';';
EXEC (#SQL);
FETCH NEXT FROM CT INTO #name;
END;
CLOSE CT;
SELECT *
FROM #AllIDSNullable;
Here is a demo
Result: