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Mysql database operation

Create database

##ExampleExample descriptionCreate a database, the name of the database is PHP
CategoryDetailed explanation
Basic syntaxCREATE DATABASE database name;
CREATE DATABASE PHP;
Example:

mysql> CREATE DATABASE PHP;

Query OK, 1 row affected (0.00 sec)

"Query OK" means the above command is executed successfully. "Query OK" is displayed after all DDL and DML (excluding SELECT) operations are executed successfully. , here it is understood that the execution is successful; "1 row affected" means that the operation only affects the records of one row in the database, and "0.00 sec" records the time when the operation was executed.

If this database already exists, the system will display:

mysql> CREATE DATABASE PHP;

ERROR 1007 (HY000): Can't create database 'PHP'; database exists

View database

Basic syntax:

CategoryDetailed explanationBasic syntaxExample descriptionDisplay all databases of the current server
show databases;
Note:

show refers to display
Database refers to the database
databases is the plural form of database, referring to all databases.

Example:

mysql> SHOW DATABASES;

+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| user ? ? ? ? ? ? |
+--------------------+
4 rows in set (0.00 sec)

Selected database

Basic syntax:

##CategoryBasic syntaxuse library name;# #ExampleExample descriptionUse database PHP

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     Detailed explanation
    use PHP
    # #
    Note: 
    use refers to use; 
    The library name is the name of the specific database that exists in the current database system; 
    Example: 
    mysql> use PHP;
    
 Database changed
    This will enter the PHP database. Of course, you can use the use statement to switch the database to be operated at any time. PHP has just been selected. Now let’s switch to the mysql database with mysql content and take a look: 
    mysql> use mysql;
    
 Reading table information for completion of table and column names
    
 You can turn off this feature to get a quicker startup with -A
    
 Database changed
    If "Database changed" appears, the switch is successful. Then, see what is in the mysql database (use the show statement the same as viewing the current database server database) 
    View the tables in the database
    After entering the library, we can see what is in the library How many data tables. 
    CategoryDetailed explanation
    Basic syntaxshow tables;
    Example descriptionShow all tables under the current database
    After using use to enter a database, you can use show tables
    Example to view the tables of the current database: 
    mysql> show tables;
    
 +--------------------------+
    
 | Tables_in_mysql |
    
 +--------------------------+
    
 | columns_priv ? ? ? ? ? ? ? ? ? ? ? ? ? ? | 
    
 |db?????????????????????????????????????????????????
 | event????????????????????????????????????
 | func ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
 | general_log |
    
 | help_category |
    
 | help_keyword |
    
 | help_relation |
    
 | help_topic |
    
 | innodb_index_stats |
    
 | innodb_table_stats |
    
 | ndb_binlog_index |
    
 | plugin |
    
 | proc ? ? ? ? ? ? ? ? ? |
    
 | procs_priv ? ? ? ? ? ? ? ? ? |
    
 | proxies_priv ? ? ? ? ? ? ? ? ? ? |
    
 | servers |
    
 | slave_master_info |
    
 | slave_relay_log_info |
    
 | slave_worker_info |
    
 | slow_log ? ? ? ? ? ? ? ? ? |
    
 | tables_priv ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | 
    
 | time_zone ? ? ? ? ? ? ? |
    
 | time_zone_leap_second |
    
 | time_zone_name |
    
 | time_zone_transition |
    
 | time_zone_transition_type |
    
 | user???????????????????????????????????????????????????
 +--------------------------+
    
 28 rows in set (0.00 sec)


    The content in these tables is information data related to users, permissions, database status, settings, etc. related to the relational database server. 
    Delete database
    CategoryDetailed explanation
    Basic syntax DROP DATABASE library name;
    ExampleDROP DATABASE PHP;
    Example descriptionDelete a database, the name of the database is liwenkai
    Note: 
    drop is in Chinese Translated to mean falling down, no longer needed
    database refers to the library
    The library name refers to the name of the library to be deleted
    Example:
    mysql> DROP DATABASE PHP;
    
 Query OK, 0 rows affected (0.01 sec)
    【Remember】Note: After the database is deleted, all data below will be deleted, so be careful and make appropriate backups before deleting. (If important data is not backed up, the actual data risk has nothing to do with this book.) 
    					
				
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    <?php
echo "Hello Mysql";
?>
    

				
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