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Simple Java DB where clause question

Joe Brigs
Ranch Hand

Joined: Jun 06, 2011
Posts: 70

I'm reading two tables the 1st one brings back a field mstr_APPL_CD that I want to use as a lookup to the 2nd query , what am I doing wrong to the 2nd where clause. I know this is very simple, but I'm having my problems. Thanks

I know this may be a JDBC question, but its pretty simple. So I posted it here
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 46349
You appear to be setting a mstr_APPL_CD String in the Java™ code, and then using a mstr_APPL_CD variable in the SQL. Those two will of course be different.
Rob Spoor

Joined: Oct 27, 2005
Posts: 20273

1) try to prevent using SELECT *. That will retrieve all columns of the record. Select only what you need; in this case that would be "SELECT APPL_CD FROM ..."

2) APPL_CD is a string, so you should enclose it in quotes.

3) you now have mstr_APPL_CD as a literal inside the statement. You need to replace that with the value of the Java variable; String concatenation should do the trick.

4) I don't think you'll be able to use the Statement after closing it. I'm absolutely sure you can't after closing its connection. Only close these when you're done with them.

5) you should be careful for SQL injection (look it up). Make sure that the APPL_CD column cannot contain any dangerous values. Otherwise use PreparedStatement instead of Statement.

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