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I know how to increase/decrease value in column.
value type is INT(11)
Command:
UPDATE table SET value = value - 1 WHERE id = 1
But when value reaches "0" it keeps decreasing.
Question: How to decrease until zero, so I don't get value (-1) in column?
Thank you for your code / ideas / suggestions
915
You can decrement value in MySQL with update command. With this, you can also restrict the value to not reach below 0. update yourTableName set yourColumnName = yourColumnName - 1 where yourColumnName > 0; To avoid the value to go below zero, you can use yourColumnName > 0.
UPDATE [table] SET [column]=0 WHERE [column] IS NULL; Null Values can be replaced in SQL by using UPDATE, SET, and WHERE to search a column in a table for nulls and replace them. In the example above it replaces them with 0.
“Every [SQL] data type includes a special value, called the null value,”0 “that is used to indicate the absence of any data value”.1. The null value does not indicate why a value is absent—it simply marks the places that do not have a data value.
SQL Server IS NULL / IS NOT NULL In SQL Server, NULL value indicates an unavailable or unassigned value. The value NULL does not equal zero (0), nor does it equal a space (' ').
Just use a conditional:
UPDATE table
SET value = value - 1
WHERE id = 1 AND value > 0;
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