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MySQL キー着脱メモ

More than 5 years have passed since last update.

テーブルに付いているキーを調べる

SHOW INDEX FROM table_name

Key_nameカラムがキーの名称です。

プライマリキー

Create文

CREATE TABLE table_name (
    column1 int(11) PRIMARY KEY
)
CREATE TABLE table_name (
    column1 int(11),
    column2 int(11),
    PRIMARY KEY (column1, column2)
)

追加

ALTER TABLE table_name
  ADD PRIMARY KEY (column1, column2);

削除

ALTER TABLE table_name
 DROP PRIMARY KEY

ユニークキー

Create文

CREATE TABLE table_name (
    column1 int(11),
    column2 int(11),
    UNIQUE KEY uk_name (column1, column2)
)

追加

ALTER TABLE table_name
  ADD UNIQUE uk_name (column1, column2);

削除

ALTER TABLE table_name
 DROP INDEX uk_name

インデックス

Create文

CREATE TABLE table_name (
    column1 int(11),
    column2 int(11),
    KEY idx_name (column1, column2)
)

追加

ALTER TABLE table_name
  ADD INDEX idx_name (column1, column2);

削除

ALTER TABLE table_name
 DROP INDEX idx_name
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