MySQL common function bitsCN.com string function CONCAT (str1, str2,...) returns the string generated by the connection parameter. If any parameter is NULL, the return value is NULL.
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Mysql> % 20 SELECT % 20 CONCAT ('My, %
MySQL functions and Usage examples
String functions
ASCII (str)Returns the ASCII value of the first character of the string 'str' (0 is returned when 'str' is an empty string)Mysql> select ASCII ('2 ');-> 50Mysql> select ASCII (2 );-> 50Mysql>
The following articles mainly describe the practical application of MySQL conditional select case. This article does not closely introduce the actual application code example, it also lists the items worth your attention in the actual operation of
MySQL floating point representation
MySQL floating-point and fixed-point types can be expressed by the type name plus (M, D). M indicates the total length of the value, and D indicates the length after the decimal point, M and D are also called
Mysql tutorial is null usage
Note that in mysql, 0 or null means false while other values mean true. The default true value of Boolean operations is 1.
The special processing of null is in the previous chapter. To determine which animal is no longer
Hive metadata parsing this article is a Hive metadata table prepared by the author. If there is any inaccuracy, please pat it. I will add it later. 1. hive0.11 meta data Table Summary online Hive0.11metastore includes the following 39 tables, mainly
MySQL floating point type, mysql floating point type
MySQL floating-point and fixed-point types can be expressed by the type name plus (M, D). M indicates the total length of the value, and D indicates the length after the decimal point, M and D are
MySQL learning notes-data definition table constraints, paging method summary, mysql learning notes
This article describes the data definition table constraints and paging methods of MySQL learning notes. We will share this with you for your
With Yan 18 study php-27th Day-the difference between the right and left inner joins
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Mysql> CREATE TABLE Boy (
Bname varchar (20),
Case value when [compare-value] THEN result [when [compare-value] THEN result ...] [ELSE result] When [condition] THEN result [when [condition] THEN result ...] [ELSE result] EndIn the return result of the first scenario, Value=compare-value. The
GROUP by (aggregate) functionsThis chapter discusses group (set) functions for a set of numeric operations. Unless otherwise stated, the group function ignores NULL values.
If you use a group function in a statement that does not contain a roup by
An introductionTopics in this sectionMulti-Table Connection queryCompound conditional Join QuerySub-queryPrepare tableCompany.employeeCompany.department#Build TableCREATE TABLE Department (ID int,name varchar (20) ; CREATE table employee (ID int
################## # # MySQL master copy # # ##################1, MySQL master-slave copy basic working principle:The master server changes the record to her binary log, copies the binary log of the primary server from the server to its intermediate
Yi, CONCAT (str1,str2,...)Returns the string that results from the connection parameter. If any one of the arguments is NULL, the return value is null.Mysql> Select Concat (' One ', ' one ', ' $ '); +------------------------+| Concat (' One ', ' a ',
How to close the database:1. Graceful way to close the database:mysqladmin-uroot-p123456 shutdown2. Script Close:/etc/init.d/mysqld stop3. Method of using kill signal (preferably not used)KILL-USR2 ' Cat path/pid 'History does not record historical
Usage of the is null statement in the mysql database
Note that in mysql, 0 or null means false while other values mean true. The default true value of Boolean operations is 1.
The special processing of null is in the previous chapter. To determine
1. CONCAT (str1, str2 ,...) Returns the string generated by the connection parameter. If any parameter is NULL, the return value is NULL. Mysqlselectconcat (112233, 33); ------------------------ | concat (, 33) | -------------------------- | --------
Select *, if (sva = 1, "male", "female") as ssva from taname where sva <> ""
12.2. Control Flow FunctionsCASE value WHEN [compare-value] THEN result [WHEN [compare-value] THEN result...] [ELSE result] end case when [condition] THEN result [WHEN
Basic MySQL Data Table operation 3: comprehensive example
1. Create a database
mysql> create database company;mysql> use company;
Ii. Create a table
1. Create an offices table
mysql> create table offices -> ( -> officeCode int(10) NOT NULL
The following articles mainly describe the practical application of MySQL conditional selectcase. This article does not closely introduce the actual application code example, it also lists the items worth your attention in the actual operation of
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