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Results tagged with unique-constraint
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user 146511
DDL UNIQUE constraints ensure that the data contained in a column, or a group of columns, is unique among all the rows in the table. The data contained in the column or columns involved is, therefore, useful to uniquely identify a row in the relevant table.
2
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Is it benefit to create a index key if unique key already exists on the same columns?
The table schema for example:
CREATE TABLE `foos` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`bar1` bigint(20) unsigned NOT NULL,
`bar2` bigint(20) unsigned NOT NULL,
PRIMARY KEY (`i …
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