Performance differences between IN and EXISTS
I often hear people wondering whether the EXISTS or the IN operator is better. Let's start by saying that the two operators behave differently when NULL values are involved (see this post).…
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Database
Writing about Database.
NOT IN vs. NOT EXISTS when NULL values are involved
NOT IN does not behave as you would expect when NULL values are involved. Suppose you have the following tables: CDFIELD DSFIELD 1 ALPHA 2 BETA TABLEA CDFIELD DSFIELD 1 GAMMA NULL DELTA…
Read articleHow to get the number of columns in a ResultSet in Java
In Java it is possible to retrieve the number of columns in a ResultSet dynamically, thanks to the ResultSetMetaData class. Here's an example: The previous code retrieves and displays the…
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