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POCopy a subset of column data from one table to another
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  1. POCopy a subset of column data from one table to another
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    copied!<p>I have two tables with identical schema. Let's name them <strong>TestTable</strong> and <strong>TestTableTemp</strong>. I need to copy just two columns from TestTableTemp to TestTable without disrupting other data. The rows in TestTable are a subset of those in TestTableTemp. Let's say the columns that I need to copy are named <strong>Column1</strong> and <strong>Column2</strong> and that they have identical primary keys reference by column <strong>primaryKey</strong>.</p> <hr> <p>In mysql I believe this could be done as such or something similar:</p> <pre><code>UPDATE TestTable, TestTableTemp SET TestTable.Column1 = TestTableTemp.Column1, TestTable.Column2 = TestTableTemp.Column2 WHERE TestTable.primaryKey = TestTableTemp.primaryKey </code></pre> <p>Sqlite does not allow for multiple tables to be defined on the update statement as can been seen in their reference data here: <a href="http://www.sqlite.org/lang_update.html" rel="nofollow">http://www.sqlite.org/lang_update.html</a></p> <p>The best I could come up with is such:</p> <pre><code>UPDATE TestTable SET Column1 = (select TestTableTemp.Column1 from TestTableTemp, TestTable where TestTable.primaryKey = TestTableTemp.primaryKey), Column2 = (select TestTableTemp.Column2 from TestTableTemp, TestTable where TestTable.primaryKey = TestTableTemp.primaryKey) WHERE EXISTS(select * from TestTableTemp where TestTable.primaryKey = TestTableTemp.primaryKey" </code></pre> <hr> <p>This gives me a syntax error near "." I am guessing this is because I cannot reference TestTable in the scalar expressions.</p> <p>Can anyone point me in the right direction? Any help is much appreciated.</p> <p>EDIT:</p> <p>I cleaned up the second query a bit. It seems to just set the Column1 and Column2 to the first row from that column from TestTableTemp.</p>
 

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