Question

I have 2 queries where one query holds the parameters to be used by another query. I have done something similar, but not with multiple parameters. Here are the queries:

SELECT [loadJob]
      ,[loadStep]
      ,[parameter]
      ,[value]
  FROM [Admin].[admin].[LoadParameters] where loadJob like 'someJobName%' and (parameter = 'targetDatabaseName' or parameter = 'targetDatasetName' or parameter = 'targetDatasetSchema')

SELECT 
      TABLE_CATALOG as DB,
      TABLE_SCHEMA,
      TABLE_NAME,
      COLUMN_NAME,
      ORDINAL_POSITION,
      COLUMN_DEFAULT,
      IS_NULLABLE,
      DATA_TYPE,
      CHARACTER_MAXIMUM_LENGTH,      
      NUMERIC_PRECISION,
      NUMERIC_PRECISION_RADIX,
      NUMERIC_SCALE,
      DATETIME_PRECISION,      
      CHARACTER_SET_NAME
FROM 
INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_CATALOG = 'TheDataBase' // From the [parameter] with name 'targetDatabaseName' get form the [value] column
AND TABLE_SCHEMA = 'data' // From the [parameter] with name 'targetDatasetSchema' get form the [value] column
AND TABLE_NAME = 'TableName'  // From the [parameter] with name 'targetDatasetName' get form the [value] column

so if my results of the first query are:

[parameter]           [value]

targetDatabaseName    SomeDataBaseName

targetDatasetSchema   data

targetDatasetName     TheTableName

the where clause in the second query would use those parameters like so:

FROM 
INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_CATALOG = 'SomeDataBaseName'
AND TABLE_SCHEMA = 'data'
AND TABLE_NAME = 'TheTableName'

I would like to group everything by table name too so I can export it to a CSV. I tried a few things, but nothing I am proud to say would work.

Answer 1

If you really don’t need the database, then you can use something like:

with FirstQuery as (
    select max(case when parameter = 'TargetDatabaseName' then value end) as DB,
           max(case when parameter = 'TargetDatasetSchema' then value end) as Schema,
           max(case when parameter = 'TargetDataSetName' then value end) as table
    from (<first query goes here>) t
)
selelect <whatever>
from Information_Schema q2 join
     FirstQuery q1
     on q1.Table_Schema = q2.Schema and
        q1.Table_Name = q2.table

The problem that I see is the database. In SQL Server, the Information_Schema tables only contain infomation about one database. To get multiple databases at once, you may have to use dynamic SQL.