Not like 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. Use Parametrized 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?
In this case, you won't have an SQL Injection problem, but you need as a matter of urgency to check everywhere else in your code to make sure that you have fixed all of them. Leave one, and you will get problems sooner or later.
When you have it parameterized, the problem may go away - but if it doesn't then you need to check your DB design, and make sure that the "Resolved On" column is set as DATE, DATETIME, or DATETIME2 - if it's VARCHAR or NVARCHAR then it will never work properly, as string comparisons are conducted character-by character, with the result of the whole comparison being the result of the first different character pair. That's useless for dates, because just as with numbers it leads to this sort order:
1
10
11
...
19
2
20
21
...
which isn't any use to you at all.
Submit an article or tip