Shulou(Shulou.com)06/01 Report--

Data modification of MYSQL

1 add a single column

An ALTER TABLE list name the parameter name (such as age) to be added by ADD (e.g. 21); [at the bottom of all columns]

B ALTER TABLE list name ADD parameter name (such as age) content (such as 21) TIRST; [the newly added column is at the top]

C ALTER TABLE list name ADD parameter name (such as age) content (such as 21) the column specified by AFIER; [the newly added column is below the column you specify]

2 add multiple columns

ALTERTABLE list name ADD parameter name to add (e.g. age) content (e.g. 21); parameter name to be added (e.g. name) content (e.g. Su Linlin); and so on [at the bottom of all columns]

3 delete a single column

ALTEERTABLE list name DROP the name of the parameter to delete (such as age)

4 delete multiple columns

ALTER TABLE list name DROP parameter name to delete (such as name), parameter name to be deleted (such as age), and so on

5 you can also add while deleting

6 add primary key constraint (there can be only one)

The name of the ALTER TABLE list is PRIMARY REY (the name of the primary key constraint to be added); (it is actually the parameter name such as the name)

7 add unique constraints (there can be multiple)

ALTER TABLE list name ADD UNIQUE (the only constraint name to be added); (in fact, the parameter name such as age)

8 add foreign key constraint

ALTERTABLE list name ADD FOREIGN KEY (foreign key parameter) REFRENCES list name (parameter name)

9 add default constraint

ALTER ABLE table name ALTER parameter SET DEFAULT default

10 remove default constraint

ALTER TABLE table name ALTER parameter DROP DEFAULT

11 to see which parameters in the list have constraints and indexes

Step 1 SHOW INDEXES FROM list name

Step 2 SHOW INDEXES FROM list name\ G

12 remove primary key constraint

ALTER TABLE table name DROP PRIMAPY KEY

13 remove unique constraint

ALTER TABLE table name DROP INDEX parameter

14 Delete foreign key constraint

ALTER TABLE table name DROP FOREIGN KEY foreign key constraint name

15 View foreign key constraint name

SHOW CREATE TABLE table name

16 delete index

ALTER TABCE table name DROP INDEX parameter name with index

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