mysql sum returns null

MySQL learning footprint record 10 -- Summary Data -- MAX (), MIN (), AVG (), SUM (), COUNT () bitsCN.com MySQL learning footprint record 10 -- Summary Data -- MAX (), MIN (), AVG (), SUM (), COUNT () Data used in this article mysql> SELECT prod_

MySQL learning footprint record 10 -- Summary Data -- data used in this article, such as MAX (), MIN (), AVG (), SUM (), and COUNT () mysql> SELECT prod_price FROM products;+------------+| prod_price |+------------+| 5.99 || 9.99 ||

Concrete Example 1. PHP Server ComponentsFor beginners, it is recommended to use the integrated server component, which already includes PHP, Apache, Mysql and other services, eliminating the time spent by developers in the tedious configuration

Sum is the standard SUM function in an SQL statement, and the SUM function returns null if there are no records that match the criteria.But in most cases, we want it to return 0 instead of NULL if the condition record is not met, so we can use the

Title MySQL SUM () COUNT () is also in the work of the recordSUM () returns the number of columns and the total number of points such as a studentEg:select sum (obj) from table is definitely the sum of the numbers of the obj columns in the table

Sum is the standard SUM function in an SQL statement, and the SUM function returns null if there are no records that match the criteria.But in most cases, we want it to return 0 instead of NULL if the condition record is not met, so we can use the

Mysql common functions, difficulties, notes, and difficulties of mysql Functions I. mathematical functionsABS (x) returns the absolute value of x.BIN (x) returns the binary value of x (OCT returns octal, HEX returns hexadecimal) CEILING (x) returns

1. Export the entire database Mysqldump-u user name-p--default-character-set=latin1 Database name > exported file name (database default encoding is latin1) Mysqldump-u wcnc-p SMGP_APPS_WCNC > Wcnc.sql 2. Export a table Mysqldump-u user name-P

Here are the MySQL commands that we often use and are very useful. Below you see # means execute command on UNIX command line, see Mysql> is currently logged on to MySQL server, execute MySQL command on MySQL client.Login to MySQL, if you are

MySQL tips 6-MySQL language structure-function bitsCN.com 1. mathematical functions are used to perform complex arithmetic operations. MySQL supports many mathematical functions. If an error occurs, all mathematical functions return NULL. (1)