MySql database query results use a table to output PHP code samples and mysql Query results. MySql database query results use a table to output PHP code samples. mysql Query results are displayed on common websites, in many databases, table data is
BitsCN.com
A colleague asks to add a field to a table (InnoDB table with existing data) without default requirements:Add the data in the previous table:
01 mysql> select * from t1; 02 + ------ + 03 | id | 04 + ------ + 05 | 1 | 06 | 2 | 07 | 3 | 08 +
Mysql database Chinese-English comparison table bitsCN.com
-- Sentence skill-- Data operationsSELECT -- retrieve data rows and columns from database tablesINSERT -- add new data rows to the database tableDELETE -- DELETE data rows from a database
Delete record bitsCN.com of some key fields in the mysql table
Clean up the duplicate data of Statistic every day [that is, the Date Server Item SubItem is identical, the Id must be different, and the Value may be the same]
Let's take a look at
MySQL extracts random data from the table to achieve random execution. the following statement is found in the manual to complete the task:
SELECT * FROM table_name order by rand () LIMIT 5;
Rand says this in the manual ::
RAND ()
RAND (N) returns
Quickly upgrade the MySQL system Table. some MySQL releases have changed the structure of the system table in the MySQL database and added new permissions or features. When you update to the new MySQL version, you should update the system tables at
7. use the WHERE clause to query records that meet the conditions in the table bitsCN.com
When using SQL statements for query operations, developers or users are not interested in all the records in the data table, but want to get the actual data
OracleDB deletes the table bitsCN.com
Delete an Oracle database table
• Move the table to the recycle bin
• If the PURGE clause is specified, the table and all its data can be deleted.
• Invalidate the subordinate object and delete the object
Mysql-merge table bitsCN.com
Mysql-merge table
[SQL]
Note:
1. the structure of each sub-table must be consistent. The structure of the master table and sub-table must be consistent,
2. the index of each sub-table exists in the merge table.
MySQL batch delete table bitsCN.com
MySQL batch delete tables
There is no existing tool in mysql for direct implementation, so the principle is to use the existing function to implement automatic spelling of drop table statements, so as to
Mysql queries records that are not in the other table in one table, bitsCN.com
Mysql queries records that are not in the same table.
Problem:
The field records for querying one table (tb1) are not in the other table (tb2 ).
Condition: The key
MYSQL foreign keys failed to be created
BitsCN.com cannot create. the error of the frm file seems to imply an error in the file permission of the operating system or other reasons, but in fact, none of these are actually. In fact, this mysql error
MySQL recursively queries the child node and parent node bitsCN.com of the tree table
Introduction: MySQL 5.0.94, which is a later version (5.5, 6, and so on) does not support recursive queries. compared with SQL Server and oracle, it is difficult
There are a large number of MyISAM log tables in the data center that need to be cleaned regularly. This is set to be done every weekend, about 10 Gb, 5-10 minutes.The event will not be written here, And the stored procedure will be directly stored .
Delete bitsCN.com from another table
Delete another table based on the table
DELETE: how can I DELETE data from multiple associated tables at the same time? Here is an in-depth explanation:
1. delete from t1 where condition
2. delete t1 from t1
Duplicate records in the MySQL Query table: bitsCN.com
Query repeated records in the MySQL table
(1)
1. search for redundant duplicate records in the table. Repeat Records determine the select * from peoplewhere peopleId in (select peopleId from
MYSQL uses mysqldump to export some data of a table.
BitsCN.com
MYSQL uses mysqldump to export some data of a table
Example:
D:/wamp/mysql/bin> mysqldump-h mysql server IP-u user name-p password database name
-- Where = "filter condition"> Export
Quickly Restore a table named mysqldump from the mysqldump file
BitsCN.com
Quickly Restore a table from the mysqldump file
In many cases, we need to restore a table from the mysqldump backup file. the common practice is to restore the SQL file to
Mysql sub-table bitsCN.com
The popularity of web in recent years has led to a boom in Mysql usage. both small enterprises and large websites have intentionally or unintentionally started using Mysql to build a new data platform. with the amount of
How to modify a table using MySQL notes: bitsCN.com
When creating a table, we will inevitably consider the problem of weeks. Therefore, the table will be modified later.
The alter table statement is required to modify a table.
Modify table nameMysql>
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