How to extract catalog name from connection string using TSQL? - tsql

Question

Say I have the following string value:
declare #cs nvarchar(100) =
'Data Source=server\instance;Initial Catalog=MyDatabase;Integrated Security=True';
What is the T-SQL to extract the string MyDatabase from #cs?
Alternately, what T-SQL function(s) should I look at for a means to figure it out for myself?

Answer 1

It's not pretty and i'm sure you could do this faster using regex / clr patindex & substrings, but a very quick and easy way is to use the split functions below to do something like this:
Example Usage:
DECLARE #cs NVARCHAR(100) = 'Data Source=server\instance;Initial Catalog=MyDatabase;Integrated Security=True';
SELECT id ,
Data ,
dbo.fnParseString(2, '=', Data)
FROM dbo.fnc_Split(#cs, ';')
WHERE Data LIKE '%Initial Catalog%'
Returns:
2 Initial Catalog=MyDatabase MyDatabase
As for the split functions, the first splts strings into tables, and the second splits strings into columns:
Split into tables:
CREATE FUNCTION dbo.fnc_Split
(
#Data VARCHAR(2000) ,
#Sep VARCHAR(5)
)
RETURNS #Temp TABLE
(
Id INT IDENTITY(1, 1) ,
Data NVARCHAR(100)
)
AS
BEGIN
DECLARE #Cnt INT
SET #Cnt = 1
WHILE ( CHARINDEX(#Sep, #Data) > 0 )
BEGIN
INSERT INTO #Temp
( data
)
SELECT Data = LTRIM(RTRIM(SUBSTRING(#Data, 1, CHARINDEX(#Sep, #Data) - 1)))
SET #Data = SUBSTRING(#Data, CHARINDEX(#Sep, #Data) + 1, LEN(#Data))
SET #Cnt = #Cnt + 1
END
INSERT INTO #Temp
( data )
SELECT Data = LTRIM(RTRIM(#Data))
RETURN
END
GO
Split into columns:
CREATE FUNCTION dbo.fnParseString
(
#Section SMALLINT ,
#Delimiter CHAR ,
#Text VARCHAR(MAX)
)
RETURNS VARCHAR(8000)
AS
BEGIN
DECLARE #NextPos SMALLINT ,
#LastPos SMALLINT ,
#Found SMALLINT
--#### Uncomment the following 2 lines to emulate PARSENAME functionality
--IF #Section > 0
-- SELECT #Text = REVERSE(#Text)
SELECT #NextPos = CHARINDEX(#Delimiter, #Text, 1) ,
#LastPos = 0 ,
#Found = 1
WHILE #NextPos > 0
AND ABS(#Section) <> #Found
SELECT #LastPos = #NextPos ,
#NextPos = CHARINDEX(#Delimiter, #Text, #NextPos + 1) ,
#Found = #Found + 1
RETURN CASE
WHEN #Found <> ABS(#Section) OR #Section = 0 THEN NULL
--#### Uncomment the following lines to emulate PARSENAME functionality
--WHEN #Section > 0 THEN REVERSE(SUBSTRING(#Text, #LastPos + 1, CASE WHEN #NextPos = 0 THEN DATALENGTH(#Text) - #LastPos ELSE #NextPos - #LastPos - 1 END))
WHEN #Section > 0 THEN SUBSTRING(#Text, #LastPos + 1, CASE WHEN #NextPos = 0 THEN DATALENGTH(#Text) - #LastPos ELSE #NextPos - #LastPos - 1 END)
ELSE SUBSTRING(#Text, #LastPos + 1, CASE WHEN #NextPos = 0 THEN DATALENGTH(#Text) - #LastPos ELSE #NextPos - #LastPos - 1 END)
END
END

Answer 2

you might find this to be a lot easier, just change the from_table to your table and the connection string field to your field.
SELECT SUBSTRING(SUBSTRING([ConnectionString], CHARINDEX('Initial Catalog=', [ConnectionString]) + LEN('Initial Catalog='), 100), 0, CHARINDEX(';', SUBSTRING([ConnectionString], CHARINDEX('Initial Catalog=', [ConnectionString]) + LEN('Initial Catalog='), 100)))
AS DbName
FROM [from_table]
i assume after taking the strings you might want to do something like this:
(iteration over the names and query some dbs)
DECLARE #DbName varchar(max)
DECLARE #QaQuery NVARCHAR(MAX);
DECLARE MY_CURSOR CURSOR
LOCAL STATIC READ_ONLY FORWARD_ONLY
FOR
SELECT SUBSTRING(SUBSTRING([ConnectionString], CHARINDEX('Initial Catalog=', [ConnectionString]) + LEN('Initial Catalog='), 100), 0, CHARINDEX(';', SUBSTRING([ConnectionString], CHARINDEX('Initial Catalog=', [ConnectionString]) + LEN('Initial Catalog='), 100)))
AS Connections
FROM [ConnTable]
OPEN MY_CURSOR
FETCH NEXT FROM MY_CURSOR INTO #DbName
WHILE ##FETCH_STATUS = 0
BEGIN
--PRINT #DbName
SET #QaQuery = N'SELECT TOP 10 [RecordID],[SomeStuff]
FROM ['+#DbName+'].[dbo].[SomeTable]
WHERE [SomeStuff] IS NOT NULL'
EXEC sp_executesql #QaQuery;
FETCH NEXT FROM MY_CURSOR INTO #DbName
END
CLOSE MY_CURSOR
DEALLOCATE MY_CURSOR