For starters, don't do that! Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Always use Parameterized queries instead.
When you concatenate strings, you cause problems because SQL receives commands like:
SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'
The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:
SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;
Which SQL sees as three separate commands:
SELECT * FROM MyTable WHERE StreetAddress = 'x';
A perfectly valid SELECT
DROP TABLE MyTable;
A perfectly valid "delete the table" command
And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.
So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?
Then you can look at why it "doesn't work" - and since that's all the info you give us I'll have to guess what that means.
Probably, it's because SQL LIKE without SQL wildcards is identical to SQL =
Which means that if your label text contains "ABC" then your LIKE will only return rows where the column exactly matches "ABC". If you want wildcard comparisons, you have to specify the wildcards!
Try this:
AND Radnik LIKE '%' + @NL + '%'
And pass
notificationLabel.Text as a parameter named
@NL
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