1. false ：0 ?true 1 切記

官方文檔：http://dev.mysql.com/doc/refman/5.0/en/numeric-type-overview.html

• ?BOOL,?BOOLEAN

  These types are synonyms for?TINYINT(1). A value of zero is considered false. Nonzero values are considered true:

  mysql> SELECT IF(0, 'true', 'false'); +------------------------+ | IF(0, 'true', 'false') | +------------------------+ | false | +------------------------+ mysql> SELECT IF(1, 'true', 'false'); +------------------------+ | IF(1, 'true', 'false') | +------------------------+ | true | +------------------------+ mysql> SELECT IF(2, 'true', 'false'); +------------------------+ | IF(2, 'true', 'false') | +------------------------+ | true | +------------------------+

  However, the values?TRUE?and?FALSE?are merely aliases for?1?and?0, respectively, as shown here:

  mysql> SELECT IF(0 = FALSE, 'true', 'false'); +--------------------------------+ | IF(0 = FALSE, 'true', 'false') | +--------------------------------+ | true | +--------------------------------+ mysql> SELECT IF(1 = TRUE, 'true', 'false'); +-------------------------------+ | IF(1 = TRUE, 'true', 'false') | +-------------------------------+ | true | +-------------------------------+ mysql> SELECT IF(2 = TRUE, 'true', 'false'); +-------------------------------+ | IF(2 = TRUE, 'true', 'false') | +-------------------------------+ | false | +-------------------------------+ mysql> SELECT IF(2 = FALSE, 'true', 'false'); +--------------------------------+ | IF(2 = FALSE, 'true', 'false') | +--------------------------------+ | false | +--------------------------------+

  The last two statements display the results shown because?2?is equal to neither?1?nor?0.

2 存儲過程中執行動態sql

官方文檔：

http://dev.mysql.com/doc/refman/5.0/en/sql-syntax-prepared-statements.html

The first example shows how to create a prepared statement by using a string literal to supply the text of the statement:

mysql> PREPARE stmt1 FROM 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse'; mysql> SET @a = 3; mysql> SET @b = 4; mysql> EXECUTE stmt1 USING @a, @b; +------------+ | hypotenuse | +------------+ | 5 | +------------+ mysql> DEALLOCATE PREPARE stmt1;

The second example is similar, but supplies the text of the statement as a user variable:

mysql> SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse'; mysql> PREPARE stmt2 FROM @s; mysql> SET @a = 6; mysql> SET @b = 8; mysql> EXECUTE stmt2 USING @a, @b; +------------+ | hypotenuse | +------------+ | 10 | +------------+ mysql> DEALLOCATE PREPARE stmt2;

Here is an additional example which demonstrates how to choose the table on which to perform a query at runtime, by storing the name of the table as a user variable:

mysql> USE test; mysql> CREATE TABLE t1 (a INT NOT NULL); mysql> INSERT INTO t1 VALUES (4), (8), (11), (32), (80);mysql> SET @table = 't1'; mysql> SET @s = CONCAT('SELECT * FROM ', @table);mysql> PREPARE stmt3 FROM @s; mysql> EXECUTE stmt3; +----+ | a | +----+ | 4 | | 8 | | 11 | | 32 | | 80 | +----+ mysql> DEALLOCATE PREPARE stmt3;

?

總結：

執行動態sql，分三步走：

1. PREPARE；

　Syntax：

PREPARE stmt_name FROM preparable_stmt

2. EXECUTE；

　　 Syntax：

　　EXECUTE stmt_name [USING @var_name [, @var_name] ...]

3. DEALLOCATE PREPARE；

　　Syntax：

{DEALLOCATE | DROP} PREPARE stmt_name

?3. 存儲過程中的事務

?語法：

START TRANSACTION [WITH CONSISTENT SNAPSHOT] BEGIN [WORK] COMMIT [WORK] [AND [NO] CHAIN] [[NO] RELEASE] ROLLBACK [WORK] [AND [NO] CHAIN] [[NO] RELEASE] SET autocommit = {0 | 1}

?

轉載于:https://www.cnblogs.com/davidwang456/p/4147132.html

總結

以上是生活随笔為你收集整理的mysql 存储过程项目小结的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。