select*fromYwhere a='1';--使用到索引a、b,未使用到c select*fromYwhere a='1'and b=2;--所有的索引列都使用到,最好的最完美的方式 select*fromYwhere a='1'and b=2and c=3;--跳过了索引a,所有的索引都未使用到(所以带头大哥不能死哟) select*fromYwhere b=2and c=3;select*fromYwhere b...
● 语法: SELECT...FROM tab WHERE EXISTS(subquery); 该语法可以理解为:将主查询的数据,放到子查询中做条件验证,根据验证结果( true 或是 false ) 来决定主查询的数据结果是否得以保留 提示 ● EXISTS(subquery) 子查询只返回 true 或者 false ,因此子查询中的 SELECT * 可以是 SELECT 1 OR SELECT X,它们...
point_selects 10 SELECT c FROM sbtest100 WHERE id=? simple_ranges 1 SELECT c FROM sbtest100 WHERE id BETWEEN ? AND ? sum_ranges 1 SELECT SUM(k) FROM sbtest100 WHERE id BETWEEN ? AND ? order_ranges 1 SELECT c FROM sbtest100 WHERE id BETWEEN ? AND ? ORDER BY c distinct_ranges ...
string (or sets errno to EOVERFLOW). Ties are broken by the IEEE round-even rule. Inspired loosely by William D. Clinger's paper "How to Read Floating Point Numbers Accurately" [Proc. ACM SIGPLAN '90, pp. 92-101]. Modifications: 1. We only require IEEE (not IEEE double-extended). ...
[session] --oltp-sp-name=STRING 指定执行测试的存储过程名 --oltp-read-only=[on|off] 仅执行select测试,默认关闭 --oltp-avoid-deadlocks=[on|off] 更新过程中忽略死锁,默认[off] --oltp-skip-trx=[on|off] 语句以bigin/commit开始结尾,默认[off] --oltp-range-size=N 范围查询的范围大小,默认 [...
MySQL Error Reference NDB Cluster API Developer Guide NDB Cluster Internals Manual MySQL Cluster Manager NDB Operator MySQL Workbench, Shell, Router MySQL client tools and middleware MySQL Workbench MySQL Shell MySQL Shell for VS Code MySQL REST Service ...
private final String USERNAME = "test"; private final String PASSWORD = "123456"; private final String DRIVER = "com.mysql.jdbc.Driver"; private final String URL = "jdbc:mysql://10.10.10.10:3306?userunicode=true&characterEncoding=utf8mb4"; private Connection connection; private PreparedStatement...
--skip-line-numbers, -L Command-Line Format --skip-line-numbers Do not write line numbers for errors. Useful when you want to compare result files that include error messages. --socket=path, -S path Command-Line Format --socket={file_name|pipe_name} Type String For connections to ...
-a 不要将SQL中数字转换成N,字符串转换成S。don't abstract all numbers to N and strings to 'S' -n NUM abstract numbers with at least n digits within names -g PATTERN 正则匹配;grep: only consider stmts that include this string -h HOSTNAME mysql机器名或者IP;hostname of db server for *...
bigNumberStrings: Enabling both supportBigNumbers and bigNumberStrings forces big numbers (BIGINT and DECIMAL columns) to be always returned as JavaScript String objects (Default: false). Enabling supportBigNumbers but leaving bigNumberStrings disabled will return big numbers as String objects only when...