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PHP学习必看的一些书 - IT书籍推荐 - 清泛网 - 专注C/C++及内核技术
...不错，对于框架介绍和开发来说
数据库相关（主要是Mysql）
《MySQL必知必会》 –极好的MySQL语法参考书
《深入浅出MySQL——数据库开发、优化与管理维护》 –很多实用的MySQL技巧
《MySQL性能调优与架构设计》 –关...
PHP学习必看的一些书 - PHP - 清泛IT论坛，有思想、有深度
...还不错，对于框架介绍和开发来说
数据库相关（主要是Mysql）《MySQL必知必会》 –极好的MySQL语法参考书《深入浅出MySQL——数据库开发、优化与管理维护》 –很多实用的MySQL技巧《MySQL性能调优与架构设计》 –关于很多架构和...
Mysql order by specific ID values
Is it possible to sort in mysql by "order by" using predefined set of column values (ID) like: order by (ID=1,5,4,3) so I would get record 1, 5, 4, 3 in that order out?
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How do I check if a column is empty or null in MySQL?
...OR some_col = ' ' (one space inserted in the string) then it works on both MySQL and Oracle, see answer of "onedaywhen". some_col = '' doesn't work on Oracle as empty strings mean NULL there.
– Johanna
May 18 '15 at 14:07
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MySQL ON vs USING?
In a MySQL JOIN , what is the difference between ON and USING() ? As far as I can tell, USING() is just more convenient syntax, whereas ON allows a little more flexibility when the column names are not identical. However, that difference is so minor, you'd think they'd just do away with USI...
What's the difference between VARCHAR and CHAR?
What's the difference between VARCHAR and CHAR in MySQL?
14 Answers
14
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How to remove constraints from my MySQL table?
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Mysql has a special syntax for dropping foreign key constraints:
ALTER TABLE tbl_magazine_issue
DROP FOREIGN KEY FK_tbl_magazine_issue_mst_users
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Does MySQL ignore null values on unique constraints?
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Yes, MySQL allows multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);...
How to change a table name using an SQL query?
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In MySQL :-
RENAME TABLE `Stu Table` TO `Stu Table_10`
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MySQL - Make an existing Field Unique
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ALTER IGNORE TABLE mytbl ADD UNIQUE (columnName);
For MySQL 5.7.4 or later:
ALTER TABLE mytbl ADD UNIQUE (columnName);
As of MySQL 5.7.4, the IGNORE clause for ALTER TABLE is removed and
its use produces an error.
So, make sure to remove duplicate entries first as IGNO...