Programming VIP

User name and password When connecting to the MySQL server with the command-line client, you should specify the user name and password for the account you want to use: shell> mysql --user=monty --password=guess db_name With a shorter option, the command should be: shell> mysql -u monty -pguess db_name Note: there must be no ...

objective Use SQL language to create and delete the database; Create, delete and update basic tables requirement In MySql Workbench, CREATE and DROP commands in SQL language are used to CREATE and delete databases.In MySql Workbench, CREATE, ALTER and DROP commands in SQL language are used to CREATE, update and delete basic tables, and t ...

The scenario with the most partitions or tables is still split for the time field. In this section, we will talk about how to better split based on the time field. According to the implementation methods of year, month and day dimensions and some details.First, take the year as the dimension to splitThe selection of date field splitting granula ...

SQL master: add, modify, delete and query four sentence patterns SQL statement: a general standard for structured query statements in relational databases. Relational database (table): Mysql, Oracle, DB2, SqlServer, etc. (1) INSERT add statement (1.1) insert all fields Note: the added data must be consistent with the order, number and type ...

Official document address: 9.1.5 Bit-Value Literals Bit value literals are written in b'val 'or 0bval notation. Val is a binary value written in 0 and 1. Leading B is not case sensitive. The leading 0b is case sensitive and cannot be written as 0b. Legal bit value literal: b'01' B'01' 0b01 Illegal bit value literal: b'2' (2 Not a bin ...

1. Definition of MySQL master-slave synchronization Master-slave synchronization enables data to be copied from one database server to other servers. When copying data, one server acts as the master and the other servers act as slave serversBecause replication is asynchronous, the slave server does not need to be connected to the master server ...

Tip: after the article is written, the directory can be generated automatically. Please refer to the help document on the right for how to generate it preface Tip: Here you can add the general contents to be recorded in this article: For example, with the continuous development of artificial intelligence, machine learning technology is ...

Index optimization analysis 1, Reasons for SQL performance degradation Poor writing of query statements Index failure: the index is built but not used Too many join (design defect or unavoidable requirement) for association query Server tuning and setting of various parameters (buffer, number of threads, etc.) 2, Common common Join qu ...

multi-table query Table used in the example: emp table dept table Syntax: select * frome Table 1,Table 2, where condition; Tip: the condition of multi table query cannot be less than - 1 of the number of tables, otherwise the Cartesian product will appear, that is, the result is the number of rows in Table 1 * the number of rows ...

SQL statement operation_ MySQL core query 2 (multi table query) 1 foreign key constraints 1.1 foreign keys The foreign key refers to the field in the slave table corresponding to the primary key of the primary table (that is, there is A column in data table A, which points to the primary key of another data table B, and this column in da ...