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mysqlsql

SQL set values of one column equal to values of another column in the same table

I have a table with two DATETIME columns.

One of them is never NULL, but one of them is sometimes NULL.

I need to write a query which will set all the NULL rows for column B equal to the values in column A.

I have tried this example but the SQL in the selected answer does not execute because MySQL Workbench doesn't seem to like the FROM in the UPDATE.

Solution

  • Sounds like you're working in just one table so something like this:

    update your_table
set B = A
where B is null