mysql function return

String function string comparison function if the result length is greater than the maximum value of the max_allowed_packet system variable, the return value of the string value function is NULL. See section 7.5.2 "Adjust server Parameters ". String

String functionsstring comparison functionsIf the length of the result is greater than the maximum value of the Max_allowed_packet system variable, the return value of the string value function is null. See section 7.5.2, "Tuning server parameters."

MySQL database functions are frequently used in actual operations. Therefore, it is best to have a certain understanding of MySQL database functions. I found this article very well on a website, I have made a special offer for you to share with you

For operations on string positions, the first position is marked as 1. ASCII (str) Returns the ASCII code value of the leftmost character of the string str. If Str is an empty string, returns 0. If STR is NULL, returns NULL. Mysql> Select ASCII (' 2

-- Add users and groups [root @ zlmlocal] groupadd [root @ zlmlocal] useradd-gmysql-ssbinnologin-doptmsyqlmysql -- create a directory [root @ zlmlocal] mkdirdatamysqlmysql_3306 {data, l -- Add users and groups[Root @ zlm local] # groupadd [Root @

MySQL obtains the current date and time stamp function bitsCN.com MySQL returns the current date, time, and timestamp. 1.1 obtain the current date + time (date + time) function: now () Mysql> select now (); + ------- + | Now () | + ------- + | 22:2

Mysql> SELECT something from Tbl_name WHERE To_days (now ()) –to_days (date_col) DayOfWeek (date) Returns the week index of date (1 = Sunday, 2 = Monday, ...). 7 = Saturday). Index values are compliant with ODBC standards. mysql> SELECT DayOfWeek ('

The following query selects the records for all date_col values within the last 30 days. Mysql> SELECT something from Tbl_name WHERE To_days (now ())-To_days (Date_col) DayOfWeek (date) Returns the week index of date (1 = Sunday, 2 = Monday, ...). 7

Date and Time functionsThis chapter discusses some functions that can be used to manipulate time values. See section 11.3, "Date and Time type" for valid formats for each time and date type with a range and a specified value. The following example

MySQL performance tuning and Architecture Design-Chapter 1 Performance Design-MySQL Replication and replication Optimization Chapter 1 scalability design-MySQL Replication Preface: MySQL Replication is a unique feature of MySQL. It can completely