SQL query error: The multi-part identifier "sys.schemas" could not be bound [closed] - sql

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I'm getting the error
The multi-part identifier sys.schemas could not be bound. The
multi-part identifier sys.tables could not be bound.
With the following code:
SET NOCOUNT ON
DECLARE #Statement NVARCHAR(MAX) = ''
DECLARE #Statement2 NVARCHAR(MAX) = ''
DECLARE #FinalStatement NVARCHAR(MAX) = ''
DECLARE #TABLE_SCHEMA SYSNAME = sys.schemas
DECLARE #TABLE_NAME SYSNAME = sys.tables
SELECT
#Statement = #Statement + 'SUM(CASE WHEN ' + COLUMN_NAME + ' IS NULL THEN 1 ELSE 0 END) AS ' + COLUMN_NAME + ',' + CHAR(13) ,
#Statement2 = #Statement2 + COLUMN_NAME + '*100 / OverallCount AS ' + COLUMN_NAME + ',' + CHAR(13) FROM
INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = #TABLE_NAME AND TABLE_SCHEMA = #TABLE_SCHEMA
IF ##ROWCOUNT = 0
RAISERROR('TABLE OR VIEW with schema "%s" and name "%s" does not exists or you do not have appropriate permissions.',16,1, #TABLE_SCHEMA, #TABLE_NAME)
ELSE
BEGIN
SELECT #FinalStatement =
'SELECT ' + LEFT(#Statement2, LEN(#Statement2) -2) + ' FROM (SELECT ' + LEFT(#Statement, LEN(#Statement) -2) +
', COUNT(*) AS OverallCount FROM ' + #TABLE_SCHEMA + '.' + #TABLE_NAME + ') SubQuery'
EXEC(#FinalStatement)
END
Where is my code wrong?

Answer 1

sysname is some character variant. You can't do
DECLARE #TABLE_SCHEMA SYSNAME = sys.schemas
DECLARE #TABLE_NAME SYSNAME = sys.tables
you need to use quotes as with char, varchar, etc.. Use
DECLARE #TABLE_SCHEMA SYSNAME = 'sys.schemas'
DECLARE #TABLE_NAME SYSNAME = 'sys.tables'
to fix the error.
Edit:
And since you apparently want to use these values to filter on the schema name and table name separately (
WHERE TABLE_NAME = #TABLE_NAME AND TABLE_SCHEMA = #TABLE_SCHEMA
) you should only assign the right part to each variable:
DECLARE #TABLE_SCHEMA SYSNAME = 'some_schema_name'
DECLARE #TABLE_NAME SYSNAME = 'some_table_name'
A schema with the name sys.schemas is unlikely to exist. As well as a table named sys.tables (I'm talking about just the name. Of course this is otherwise a qualified identifier including the schema.).
E.g.:
DECLARE #TABLE_SCHEMA SYSNAME = 'sys'
DECLARE #TABLE_NAME SYSNAME = 'tables'
(But sys.tables doesn't seem to bee listed in information_schema.columns. But I guess your not after system but "regular" tables anyway.)

Answer 2

I think what you are looking for has similarities to what this person achieved here:
recursively go through each table and find the total number of NULL values.
But do bear in mind that this can take a while depending on the size of your database.
<!-- language: lang-SQL -->
DECLARE #schemaName AS sysname;
DECLARE #tableName AS sysname;
DECLARE #columnName AS sysname;
DECLARE #schema_id AS int;
DECLARE #object_id AS int;
DECLARE #column_id AS int;
DECLARE #isNullable AS bit;
DECLARE #lastSchema_id AS int;
DECLARE #lastTable_id AS int;
DECLARE #recordCount AS bigint;
DECLARE #nullCnt AS bigint;
DECLARE #SQL as nvarchar(max);
DECLARE #paramDefinition NVARCHAR(max);
if exists(select name from tempdb..sysobjects where name LIKE'#Columns%')
DROP TABLE #Columns;
CREATE TABLE #Columns (
schema_id int,
object_id int,
column_id int,
schemaName sysname,
tableName sysname,
columnName sysname,
recordCnt bigint,
nullCnt bigint,
nullPct numeric(38,35) );
-- Set to the #lastSchema_id and #lastTable_id to NULL so that the first
-- loop through the cursor the record count is generated.
SET #lastSchema_id = NULL;
SET #lastTable_id = NULL;
-- List of all the user schemas.tables.columns
-- in the database
DECLARE c_Cursor CURSOR FOR
SELECT schemas.schema_id
, all_objects.object_id
, all_columns.column_id
, schemas.name AS schemaName
, all_objects.name AS tableName
, all_columns.name AS columnName
, all_columns.is_nullable
FROM sys.schemas
INNER JOIN sys.all_objects
ON schemas.schema_id = all_objects.schema_id
AND all_objects.type = 'U'
INNER JOIN sys.all_columns
ON all_objects.object_id = all_columns.object_id
ORDER BY schemas.schema_id
, all_objects.object_id
, all_columns.column_id;
OPEN c_Cursor;
FETCH NEXT FROM c_Cursor
INTO #schema_id
, #object_id
, #column_id
, #schemaName
, #tableName
, #columnName
, #isNullable;
-- Loop through the cursor
WHILE ##FETCH_STATUS = 0
BEGIN
-- Get the record count for the table we are currently working on if this is
-- the first time we are encountering the table.
IF ( ( #schema_id <> #lastSchema_id ) OR ( #object_id <> #lastTable_id )
OR ( #lastSchema_id IS NULL ) OR ( #lastTable_id IS NULL ) )
BEGIN
SET #SQL = N'SELECT #recordCount = COUNT(1) FROM ' + QUOTENAME(#schemaName) + N'.' + QUOTENAME(#tableName) + ';';
SET #paramDefinition = N'#recordCount bigint OUTPUT';
exec sp_executesql #SQL,
#paramDefinition,
#recordCount = #recordCount OUTPUT;
END
-- If the column is NOT NULL, there is no reason to do a count
-- Set the nullCnt and nullPct to 0
IF ( #isNullable = 0 )
BEGIN
INSERT INTO #Columns
( [schema_id]
, [object_id]
, column_id
, schemaName
, tableName
, columnName
, recordCnt
, nullCnt
, nullPct )
VALUES
( #schema_id
, #object_id
, #column_id
, #schemaName
, #tableName
, #columnName
, #recordCount
, 0
, 0.0 );
END
-- If the column is NULL, count the number of NULL fields in the table.
ELSE
BEGIN
SET #SQL = N'SELECT #nullCnt = COUNT(1) FROM ' + QUOTENAME(#schemaName) + N'.' + QUOTENAME(#tableName) +
N' WHERE ' + QUOTENAME(#columnName) + N' IS NULL;';
SET #paramDefinition = N'#nullCnt bigint OUTPUT';
PRINT #SQL;
exec sp_executesql #SQL,
#paramDefinition,
#nullCnt = #nullCnt OUTPUT;
INSERT INTO #Columns
( [schema_id]
, [object_id]
, column_id
, schemaName
, tableName
, columnName
, recordCnt
, nullCnt
, nullPct )
VALUES
( #schema_id
, #object_id
, #column_id
, #schemaName
, #tableName
, #columnName
, #recordCount
, #nullCnt
-- USE NULLIF in case there are no recods in the table
, ISNULL( #nullCnt * 1.0 / NULLIF( #recordCount, 0) * 100.0, 0 ) );
END
-- Set the #lastSchema_id and #lastTable_id so that on
-- the next loop, if it's the same table there is no
-- need to recount the columns for the table.
SET #lastSchema_id = #schema_id;
SET #lastTable_id = #object_id;
FETCH NEXT FROM c_Cursor
INTO #schema_id
, #object_id
, #column_id
, #schemaName
, #tableName
, #columnName
, #isNullable;
END;
CLOSE c_Cursor;
DEALLOCATE c_Cursor;
SELECT *
FROM #Columns;
https://social.msdn.microsoft.com/Forums/sqlserver/en-US/3e097cad-f355-4f7e-b265-f7e6137670bf/challenge-how-to-count-nulls-for-each-column-in-every-table-in-vldb-etc?forum=transactsql