How to use loop for like or ilike function? - sql

Question

I am currently asked to validate the result of a global search which to find all records containing some keywords cross whole database. To do so, I need to check all the rows in each table that have keywords. The result for this global search is ready and partially of the result looks like the one below:
table_name
column_name
keyword
cnt
Wf_Process
Name_EN
FEC
11
Wf_Process
FTABLENAME
GB
14
ICCClass
Name_EN
GB
4
What I am trying to do is using the 'like' operator to extract all the data in each table where columns containing keywords. That is, I will use query such as:
select distinct Name_EN, FTABLENAME from Wf_Process where Name_EN like '%FEC%' or FTABLENAME like '%GB%'
and
select distinct Name_EN from ICCClass where Name_EN like '%GB%'
to pull out all data I need in whole database. If I only have three records, then it is not a problem. However my result returned over thousands tables have more than 10K rows containing keywords in total. Therefore, I was trying to use a loop to do this mission but I failed.
My question therefore is, does anyone have any idea to write a loop to do the 'like' search for all the tables in one time? Or is there another way rather than loop can do this in SQL Server?
Thank you very much!

Answer 1

You need dynamic SQL for this. You can generate a big UNION ALL query of all the tables together.
DECLARE #sql nvarchar(max) = (
SELECT STRING_AGG(CAST('
SELECT
' + QUOTENAME(con.table_name, '''') + ' table_name,
' + QUOTENAME(con.column_name, '''') + ' column_name,
' + QUOTENAME(con.keyword, '''') + ' keyword,
COUNT(*) cnt
FROM ' + QUOTENAME(s.name) + '.' + QUOTENAME(t.name) + ' t
WHERE t.' + QUOTENAME(c.name) + ' LIKE ' + QUOTENAME('%' + con.keyword + '%', '''')
AS nvarchar(max)), '
UNION ALL')
FROM YourConditions con
JOIN sys.tables t ON t.table_name
JOIN sys.schemas s ON s.schema_id = t.schema_id
JOIN sys.columns c ON c.object_id = t.object_id
WHERE t.name = con.table_name
AND c.name = con.column_name
);
PRINT #sql; -- your friend
EXEC sp_executesql #sql;
There are more efficient ways to do this if there are many columns or keywords per table, but this should get you started.

Answer 2

The question looks odd, thou can be done via dynamic sql, but not as a regular solution more like a one off or POC/test.
use tempdb
GO
drop table if exists search_result
go
create table search_result (
table_name sysname
,column_name sysname
,keyword varchar(100))
go
insert into search_result values
('Wf_Process', 'Name_EN', 'FEC')
,('Wf_Process' , 'FTABLENAME', 'GB')
,('ICCClass', 'Name_EN', 'GB')
GO
drop table if exists result
create table result (val varchar(500))
go
declare #col sysname
declare #tab sysname
declare #kw varchar(100)
declare #sql varchar(1000)
while exists (select * from search_result)
begin
select top 1
#tab = table_name
, #col = column_name
, #kw = keyword
from search_result
set #sql = concat('insert into result select ', #col, ' from ', #tab, ' where ', #col, ' like ''%', #kw, '%''' )
print(#sql)
exec (#sql)
delete from search_result
where table_name = #tab and column_name = #col and keyword = #kw
end
GO
select * from result

Answer 3

--initially trying to get all the column name with its respective table name, finding out if there is that particular keyword in all table,
--if yes, insert into temp table, if there aint keyword, it will insert the record too but the count of record will be zero.
--trying to make it dynamic and running it inside the loop by assigning row number to each table with different column.
IF OBJECT_ID('tempdb..#TEMP') IS NOT NULL
DROP TABLE #TEMP
CREATE TABLE #TEMP (TABLE_NAME NVARCHAR(200), COLUMN_NAME NVARCHAR(200), KEYWORD NVARCHAR(200), CNT INT)
DECLARE #TABLE NVARCHAR(200)
DECLARE #TABLE_ID INT
SET #TABLE_ID = 1
DECLARE #TABLE_NAME NVARCHAR (200)
DECLARE #FOR_LOOP INT
DECLARE #COLUMN NVARCHAR(200)
DECLARE #COLUMN_NAME NVARCHAR(200)
--TOTAL NO OF RECORDS FOR LOOP
SET #FOR_LOOP = (SELECT COUNT(*)
FROM SYS.tables T
JOIN SYS.all_columns C ON T.object_id = C.object_id
JOIN INFORMATION_SCHEMA.TABLES S ON S.TABLE_NAME = T.name)
DECLARE #STRINGS NVARCHAR(200)
SET #STRINGS = '%FEC%' --------->ENTER YOUR KEYWORD HERE, TRY ONE AT A TIME
DECLARE #COUNT INT
WHILE #TABLE_ID <= #FOR_LOOP
BEGIN
SET #TABLE = (SELECT CAST(TABLE_NAME AS NVARCHAR(200))
FROM
(SELECT ROW_NUMBER()OVER(ORDER BY T.NAME) TABLE_ID
,S.TABLE_SCHEMA SCHEMA_NAME ,T.NAME TABLE_NAME, C.name COLUMN_NAME
FROM SYS.tables T
JOIN SYS.all_columns C ON T.object_id = C.object_id
JOIN INFORMATION_SCHEMA.TABLES S ON S.TABLE_NAME = T.name)A
WHERE TABLE_ID = #TABLE_ID)
SET #TABLE_NAME = '['+#TABLE+']'
SET #COLUMN = (SELECT CAST(COLUMN_NAME AS NVARCHAR(200))
FROM
(SELECT ROW_NUMBER()OVER(ORDER BY T.NAME) TABLE_ID
,S.TABLE_SCHEMA SCHEMA_NAME ,T.NAME TABLE_NAME, C.name COLUMN_NAME
FROM SYS.tables T
JOIN SYS.all_columns C ON T.object_id = C.object_id
JOIN INFORMATION_SCHEMA.TABLES S ON S.TABLE_NAME = T.name)A
WHERE TABLE_ID = #TABLE_ID)
SET #COLUMN_NAME = '['+#COLUMN+']'
DECLARE #EXEC NVARCHAR(200) = 'SELECT ' + #COLUMN_NAME +' FROM ' + #TABLE_NAME + ' WHERE ' + #COLUMN_NAME + ' LIKE ' + ''''+#STRINGS+''''
--THERE MUST BE ANOTHER WAY TO REPLACE SP_EXECUTESQL FOR BETTER PERFORMANCE, AS IT WILL BE EXECUTED AS MANY TIMES AS THERE ARE RECORDS IN #FOR_LOOP
EXEC SP_EXECUTESQL #EXEC
SET #COUNT = (SELECT ##ROWCOUNT)
IF (SELECT ##ROWCOUNT) >=1
BEGIN
INSERT INTO #TEMP VALUES
(#TABLE_NAME, #COLUMN_NAME, #STRINGS, #COUNT)
SET #TABLE_ID = #TABLE_ID + 1
END
ELSE
--DONT KNOW WHY THIS ELSE PART IS NOT TOUCHED, WHEREAS I THINK IT SHOULD HAVE
BEGIN
PRINT 'RECORD NOT FOUND'
END
END
GO
--AFTER THE ABOVE BLOCK IS EXECUTED THEN TRY RUNNING BELOW ONE
SELECT *FROM #TEMP WHERE CNT>0
--THERE MAY BE MULTIPLE ERROS, MUST BE EDITED AND CAN MAKE IT AS A PROCEDURE TOO.