how to update a table field with a variable value calculated

Question

$average is the variable that i want should replace/update price field in a table. Table structure is:

and $key is the variablethrough which i get the nid of this table.

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nid | sku     | price
7   |  prod-1 | 10
9   | prod-2  | 12

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update query i am using is:

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$query =db_query("UPDATE products a SET a.price = $average WHERE a.sku = $key");

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but it gives an error:

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PDOException: SQLSTATE[22007]: Invalid datetime format: 1292 Truncated incorrect DOUBLE value: 'tshirtm': UPDATE products a SET a.price = 1.75 WHERE a.sku = 7; Array ( ) in formModule_form_submit() (line 233 of D:\xampp\htdocs\olinestore\store\sites\all\modules\formModule\formModule.module).

Answer 1

I notice that the WHERE criteria is sku=7 -- however in your sample data, sku is a varchar? Was this intended on being nid?

Possibly the problem is your data type of your price column is an integer but you're trying to update it to a decimal. Depending on your RDBMS, this can easily be resolved.

Good luck.

Answer 2

When $key corresponds to nid, you shouldn't use sku. Try this:

$query =db_query("UPDATE products a SET a.price = $average WHERE a.nid = $key");