What is the use of the Decode Function in SQL? As we discussed earlier, a Decode function in Oracle helps us to add if-then-else logic to a query procedurally. It compares an expression with each search value one after another. Suppose, if an expression is found equal, the same is ret...
插入空值: mysql> alter table test add column height varchar(8); Query OK, 0 rows affected (0.02 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> insert into test values(7,'gary',14,''); Query OK, 1 row affected (0.00 sec) mysql> select * from test; +---+---+---+---+ ...
DECODE function in Standard Query Language (SQL) is used to add procedural IF – THEN – ELSE like statements to a query. It compares a given expression with each search value one by one and returns a result on the basis of outcomes received from the comparison. A decode function basically...
Based on the Oracle SQL query shown in the diagram, here is the extracted SQL code and the result set: SQL Query: SELECT STATE, DECODE(STATE, 'HI', 'Remote US state', 'AK', 'Continental US state', 'Contiguous US state') LOCATION FROM CUSTOMER; ...
The function can be used only in the WHERE clause of a query. It takes as an argument a condition and returns TRUE if the condition is FALSE or UNKNOWN and FALSE if the condition is TRUE. 语法– ```sql LNNVL( condition(s) ) ``` 示例– ```sql SELECT COUNT(*) FROM employees ...
set global slow_query_log=on; 9) 查看当前状态 status; 10)查询当前所在的库 select database(); 11) 查看当前数据库队列 show processlist; 12) 计算某个库中数据的大小 select concat(round(sum(data_length/1024/1024)),'MB') as total from information_schema.tables where table_schema='数据库名称...
3回答 在foreach()循环中优化SQL查询 、 否则,我如何才能在不将查询放入foreach循环的情况下获得name?PHP:foreach($material_decode as $material_id=>$material_value) $forge_materials=mysql_fetch_assoc(mysql_query('SELECT `name` FROM ` 浏览2提问于2015-08-07得票数 2 回答已采纳 ...
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3,mysql create view 不能有子查询 ( 视图 第1349号错误解决方法)ERROR 1349 (HY000): View's SELECT contains a subquery in the FROM clause 我的解决办法是 视图中包含视图 4,mysql CONCAT_WS和CONCAT的区别 首先看一下oracle当前的视图创建sql: ...
DECODE函数的作用:它可以将输入数值与函数中的参数列表相比较,根据输入值返回一个对应值。函数的参数列表是由若干数值及其对应结果值组成的若干序偶形式。当然,如果未能与任何一个实参序偶匹配成功,则函数也有默认的返回值。 区别于SQL的其它函数,DECODE函数还能识别和操作空值。