split string by comma in sql query

Assuming you are using SQL Server, you need to concatenate , from both sides of the column so you can match the value you are searching.

SELECT  *
FROM    TableName
WHERE   ',' + csvColumn + ',' LIKE '%,' + 'split_item1' + ',%' OR
        ',' + csvColumn + ',' LIKE '%,' + 'split_item2' + ',%'

Concatenation symbol differs on every dbms, CONCAT() for MySQL, || for Oracle.

• SQLFiddle Demo for SQL Server
• SQLFiddle Demo for MySQL
• SQLFiddle Demo for Oracle

You can use the follow code (created for sqlserver).

Create Function FUN_STRING_SPLIT(@text varchar(max), @separator varchar(10))
Returns @Result Table 
(
   POSITION INT IDENTITY(1,1) NOT NULL, VALUE VARCHAR(max) 
)
As 
Begin
    Declare @ini int = 1, @end int = 0

    While @end <= LEN(@text)
    Begin
        if @end > 0 set @ini = @end + LEN(@separator)
        if @ini > 0 set @end = CHARINDEX(@separator, @text, @ini)
        if @end = 0 set @end = LEN(@text) + 1

        Insert Into @Result (VALUE) Values (SUBSTRING(@text,@ini,@end - @ini))
    End
    Return
End

Then use like:

Select * From FUN_STRING_SPLIT('Word1,Word2,Word2,Etc..', ',');

select * from fromSplitStringSep('Word1 wordr2 word3',' ')

CREATE function [dbo].[SplitStringSep] 
    (
        @str nvarchar(4000), 
        @separator char(1)
    )
    returns table
    AS
    return (
        with tokens(p, a, b) AS (
            select 
                1, 
                1, 
                charindex(@separator, @str)
            union all
            select
                p + 1, 
                b + 1, 
                charindex(@separator, @str, b + 1)
            from tokens
            where b > 0
        )
        select
            p-1 zeroBasedOccurance,
            substring(
                @str, 
                a, 
                case when b > 0 then b-a ELSE 4000 end) 
            AS s
        from tokens
      )