mysql查询数据库的相关内容

文章 2022-12-05 来自：开发者社区

mysql查询所有数据库、表、字段常用sql语句

查询所有数据库名称：SELECT `SCHEMA_NAME` FROM `information_schema`.`SCHEMATA` 查询特定数据库下的所有表//查询数据库名称为lml下的所有表 select table_name from information_schema.tables where table_schema='lml' ；查询特定表下的所有字段select COLUM.....

文章 2022-10-13 来自：开发者社区

mysq优化---mysql执行计划解释、优化查询、数据库结构、服务器

执行计划解释EXPLAIN select id from test where age=18 and EXISTS (select name from test where name ='张三')索引类型普通索引唯一索引单列索引组合索引注意，只支持，最左索引:查看索引语句SHOW INDEX FROM TEST优化查询注意哪些情况索引不生效我们知道索引可以加快查询，但是有些情况索引不生效:1...

文章 2022-05-31 来自：开发者社区

MySQL - 查询数据库里所有表名和字段名

查询数据库里所有表名和字段名的语句 SQL 查询所有表名 SELECT NAME FROM SYSOBJECTS WHERE TYPE='U'SELECT * FROM INFORMATION_SCHEMA.TABLES 查询表的所有字段名 SELECT NAME FROM SYSCOLUMNS WHERE ID=OBJECT_ID(' 表名' )SELECT * FROM ...

文章 2022-05-19 来自：开发者社区

【Java】【MySQL】数据库存储的日期是字符类型，查询指定日期时间区间是用数据库的方法STR_TO_DATE().

一、问题与分析遇到的问题：找出xxx到期剩余x天的所有服务场景限制条件：数据库表里存的是字符类型的日期格式（yyyy-MM-dd）分析：当前需要解决的是表里的字段存储日期格式的类型是字符类型，最终想到的是利用STR_TO_DATE()的方法。（最后完美提高了几倍效率）二、实现过程一个表数据与表结构，如下图：执行sql语句SELECT * from t_doc_info WHERE 1 = 1 .....

文章 2021-12-12 来自：开发者社区

Mysql 查询数据库数据量

Mysql查询数据库数据量SELECT table_name AS '表名', table_rows AS '记录数', TRUNCATE (data_length / 1024 / 1024, 2) AS '数据容量(MB)', TRUNCATE (index_length / 1024 / 1024, 2) AS '索引容量(MB)' FROM inf...

问答 2021-11-01 来自：开发者社区

MySQL查询当前数据库版本的命令是哪个操作呢？

文章 2016-12-29 来自：开发者社区

【MySQL】查询某个数据库有多少张数据表

SELECT COUNT(*) TABLES, table_schema FROM information_schema.TABLES WHERE table_schema = 'performance' GROUP BY table_schema; 这里 table_schema = '数据库名字'

问答 2016-08-17 来自：开发者社区

mysql视图查询，站点和数据库放到云服务器后，视图查询结果总是为空

在我自己电脑上正常，能查询出结果

问答 2016-02-20 来自：开发者社区

mysql中如何查询当前记录在数据库中的行数

mysql中如何查询当前记录在数据库中第多少行，怎么写sql。求指导，谢谢！

问答 2016-02-07 来自：开发者社区

如何在mysql里查询含特定表的数据库？

例如在mysql中共有10个数据库，其中2个数据库含有表“wp_config”，怎么通过sql查询到含有表“wp_config”的数据库？

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更新时间 2025-01-20 12:58:21

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