mysql Lesson

Modifying one or more rows of data in Table:

SELECT*FROM student;
+----+------+------+
| id | name | ban  |
+----+------+------+
|  1 | yy   | 1913 |
|  7 | ss   | 1923 |
|  8 | 许   | 1913 |
|  9 | 应   | 1913 |
| 10 | Aron | 1913 |
+----+------+------+
5 rows in set

UPDATE student SET name="yiyq"WHERE ban=1913;
Query OK, 4 rows affected
Rows matched: 4  Changed: 4  Warnings: 0

检查：SELECT*FROM student;
+----+------+------+
| id | name | ban  |
+----+------+------+
|  1 | yiyq | 1913 |
|  7 | ss   | 1923 |
|  8 | yiyq | 1913 |
|  9 | yiyq | 1913 |
| 10 | yiyq | 1913 |
+----+------+------+
5 rows in set

Delete the data: the FROM accout the SELECT *;
+ ---- + ------ + ------- +
| the above mentioned id | name | Money |
+ ---- + ------ + - + ------
|. 1 | A | 800 |
| 2 | B | 1200 |
+ ---- + ------ + ------- +
2 in rows SET

DELETE FROM accout WHERE name="a";
Query OK, 1 row affected

 SELECT*FROM accout;
+----+------+-------+
| id | name | money |
+----+------+-------+
|  2 | b    |  1200 |
+----+------+-------+
1 row in set

 

When you create a table to create the index:

INDEX id;

TRUNCATE also delete the data, but it is to delete a table in a reconstruction of the same table.

 

 

Create an index:

CREATE [UNIQUE / FULLTEXT / SPATIAL] INDEX ON table index name (field name [(length)] [ASC / DESC]);

The general index without anything,

UNIQUE: optional parameter represents a unique constraint,

FULLTEXT: optional parameter that indicates the full text of the constraints

SPATIAL: optional parameter represents the spatial constraints

 

ALTER created by:

ALTER TABLE table name ADD [UNIQUE / FULLTEXT / SPATIAL] INDEX index name (field [(length)] [ASC / DESC]);

Ordinary Index: ALTER TABLE book ADD INDEX inter_id (bookid);

 

 

Delete the index:

1.ALTER TABLE table DROP INDEX field name;

2.DROP INDEX index name ON table name;