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| -rw-r--r-- | docs/Dealing-with-SQL-files.md | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/docs/Dealing-with-SQL-files.md b/docs/Dealing-with-SQL-files.md index b25fc18..69a97f2 100644 --- a/docs/Dealing-with-SQL-files.md +++ b/docs/Dealing-with-SQL-files.md @@ -58,6 +58,25 @@ Good: UPDATE `table_1` SET `field_1` = 'someValue' WHERE `entry` IN (1000, 2000, 3000); ``` +#### Flags + +For flags (2^) columns, when you remove or add a flag, it is better not to override the existing value as flags are combined values. + +For example, given a flag with value `128`, this is how it would be to add, remove and invert it: + +```sql +-- ADD AN EXTRA FLAG (|) +UPDATE `table_1` SET `field_1` = `field_1` | 128 WHERE `entry` = 1000; + +-- REMOVE AN EXTRA FLAG (& ~) +UPDATE `table_1` SET `field_1` = `field_1` & ~128 WHERE `entry` = 1000; + +-- INVERT A FLAG (if present = removed, if absent = added) (^) +UPDATE `table_1` SET `field_1` = `field_1` ^ 128 WHERE `entry` = 1000; +``` + +This way, you will make sure that your query will only affect that specific flag, leaving all the other flags unchanged. + ### DELETE Bad: |