问题很明显,由于OR语句导致索引无法正常使用,将OR调整为UNION ALL,调整后的SQL语句为: SELECT*FROMbs_serial_tracWHEREGOODS_NO='4418095740626'ANDPARENT_CODE='F9G7S19722007485'UNIONALLSELECT*FROMbs_serial_tracWHEREGOODS_NO='4418095740626'ANDSERIAL='F9G7S19722007485'ANDPARENT_CODE<>'F9G7S19722007485' 查...
SELECT employee_id,last_name,CASE department_id WHEN( SELECT department_id FROM departments WHERE location_id=1800) THEN 'Canada' ELSE 'USA' END location FROM employees; 5、子查询其他问题 空值:子查询为空值时主查询没有行返回 非法使用:多行子查询使用单行比较符 三、多行子查询 多行子查询也称为...
sum(case when sex='1' then population else 0 end) as 男, --男性人口 sum(case when sex='2' then population else 0 end) as 女 --女性人口 from table_a group by country; 1. 2. 3. 4. 5. 这样我们使用Select,完成对二维表的输出形式,充分显示了Case函数的强大。 三. 在Check中使用Case...
MySQL Enterprise Edition The most comprehensive set of advanced features, management tools and technical support to achieve the highest levels of MySQL scalability, security, reliability, and uptime. Learn More » MySQL for OEM/ISV Over 2000 ISVs, OEMs, and VARs rely on MySQL as their products...
WHEN price > 100 AND price <= 500 THEN '一般' ELSE '便宜' END AS label FROM products; 上述语句中,我们使用CASE WHEN OR来设置不同的条件判断,当商品价格大于1000或者在500到1000之间时,标签为“昂贵”;当商品价格大于100并且小于等于500时,标签为“一般”;否则标签为“便宜”。 2.处理多个条件 除了处...
utf8_genera_ci不区分大小写,ci为case insensitive的缩写,即大小写不敏感, utf8_general_cs区分大小写,cs为case sensitive的缩写,即大小写敏感,但是目前MySQL版本中已经不支持类似于***_genera_cs的排序规则,直接使用utf8_bin替代。 utf8_bin将字符串中的每一个字符用二进制数据存储,区分大小写。 那么,同样是...
01. ||, OR, XOR 02. &&, AND 03. BETWEEN, CASE, WHEN, THEN, ELSE 04. =, <=>, >=, >, <=, <, <>, !=, IS, LIKE, REGEXP, IN 05. | 06. & 07. <<, >> 08. -, + 09. *, /, DIV, %, MOD 10. ^ 11. - (unary minus), ~ (unary bit inversion) ...
MySQL WHEN OR THEN函数 MySQL WHEN OR THEN函数的实现 简介 MySQL中的CASE语句是一种条件语句,可以根据不同的条件执行不同的操作。其中,WHEN和THEN是CASE语句的两个关键字,用于指定条件和条件满足时的执行操作。本文将向你介绍如何使用MySQL的WHEN OR THEN函数来实现条件判断和执行操作。
2Table and database names are stored on disk using the lettercase specified in theCREATE TABLEorCREATE DATABASEstatement, but MySQL converts them to lowercase on lookup. Name comparisons are not case-sensitive. This worksonlyon file systems that are not case-sensitive!InnoDBtable names and view...
Applications should be prepared to handle the very rare case that a hashing function produces the same value for two different input values. One way to make collisions detectable is to make the hash column a primary key. Note Exploits for the MD5 and SHA-1 algorithms have become known. You...