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MYSQL OR vs IN performance
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Performance reason (quoting MariaDB(a MySQL new free branch) docs): Returns 1 if expr is equal to any of the values in the IN list, else returns 0. If all values are constants, they are evaluated according to the type of expr and sorted. The search for the item t...
How can I get enum possible values in a MySQL database?
...wns with enum possible values from a DB automatically. Is this possible in MySQL?
24 Answers
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Is there a MySQL command to convert a string to lowercase?
I have a MySQL database of keywords that are presently mixed-case. However, I want to convert them all to lowercase. Is there an easy command to do this, either using MySQL or MySQL and PHP?
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MySQL: Fastest way to count number of rows
Which way to count a number of rows should be faster in MySQL?
12 Answers
12
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Delete all Duplicate Rows except for One in MySQL? [duplicate]
How would I delete all duplicate data from a MySQL Table?
2 Answers
2
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App Inventor 2 列表代码块 · App Inventor 2 中文网
...用给定的变量名称 item 来引用当前列表项。
此处 是有关如何使用该块的教程。
创建过滤列表
通过保持输入列表中的每个项目满足测试来创建一个新列表。
主体是一个布尔表达式，用于检查项目是否通过...
How do I change the data type for a column in MySQL?
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http://dev.mysql.com/doc/refman/5.1/en/alter-table.html
ALTER TABLE tablename MODIFY columnname INTEGER;
This will change the datatype of given column
Depending on how many columns you wish to modify it might be best to generate a scri...
How do I update if exists, insert if not (AKA “upsert” or “merge”) in MySQL?
...SERT a row when it does not exist, or to UPDATE if it exists, using one MySQL query?
2 Answers
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搭建高可用mongodb集群（二）—— 副本集 - 大数据 & AI - 清泛网 - 专注C/...
...切换连接？目前需要手工切换。
主节点的读写压力过大如何解决？
从节点每个上面的数据都是对数据库全量拷贝，从节点压力会不会过大？
数据压力大到机器支撑不了的时候能否做到自动扩展？
这篇文章看完这些问题就...
MySQL pagination without double-querying?
I was wondering if there was a way to get the number of results from a MySQL query, and at the same time limit the results.
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