MySQL string function usage instructions bitsCN.com usually uses the entire string as the operation object, such: search for a substring in a substring, obtain a substring, insert a substring at a certain position in the substring, and delete a
MysqlGBK encoding is equivalent to Chinese or Spanish characters, so the total number of characters is 2selectchar_length (character). One Chinese Character occupies 2 bytes, therefore, the total length of the byte is 4 selectlength (character); 1
Mysql string matching requirement table data: Java code mysql> select * from test; + ---- + ------- + | id | name | + ---- + ------- + | 1 | abc ** | + ---- + ------- + 1 row in set (0.00 sec) I want to match abcde, that is, a * represents a
Suppose there is a table: CREATETABLEusers (idint (6) NOTNULLAUTO_INCREMENT, PRIMARYKEY (id), user_nameVARCHAR (20) NOTNULL, emailsVARCHAR (50) NOTNULL); initialize the table and add some records. TruncatetableusersINSERTINTOusers (user_name, emails)
MySQL strings have many column types. The following describes the differences between MySQL strings and column types. We hope that you can have a deeper understanding of MySQL string types.
1.
First, the differences between CHAR, VARCHAR, TEXT,
MySQL string segmentation user-defined function bitsCN.com
/*** Method 1 */select * from dbo. split ('01 _ 02000003 ',' _ ') error. the returned result is not the result we originally wanted: ------------------- -- expected result 01 02 03 ----------
MySQL string type conversion time type bitsCN.com
If the MySQL database uses the varchar (or char) type at a certain time, it is convenient for the system to use it, instead of converting the time type to adapt to different database versions, to
MySQL string function Daquan if the result length is greater than the server parameter max_allowed_packet, the string value function returns NULL.
For operations on the string position, the first position is marked as 1.
ASCII (str)Returns the
Ref: [Abusing MySQL string arithmetic for tiny SQL Injections]
Let's look at this scenario first.The table structure is as follows:
mysql> desc admin;+----------+--------------+------+-----+---------+----------------+| Field | Type | Null
How to insert random string data in mysql, mysql string
Application scenarios:Sometimes it is necessary to test the records inserted into the database, so these scripts are very necessary.
Create a table:
CREATE TABLE `tables_a` ( `id` int(10) NOT
For sorting of mysql string fields, I have A varchar type field. There are three pieces of data in the order by a desc, the order is as follows: 2013.03, 2013.02, 2013.04
How can I keep the latest time at the top? Without modifying the field type
ASCII (char) returns the ASCII code value of a characterBit_length (str) returns the bit length of a stringCONCAT (S1,S2...,SN) to concatenate s1,s2...,sn into a stringConcat_ws (SEP,S1,S2...,SN) joins the S1,S2...,SN into a string and uses the Sep
Method One:SELECT * from the users WHERE emails like "%[email protected]%";Method Two:Use the MySQL string function find_in_set ();SELECT * from Users WHERE find_in_set (' [email protected] ', emails);This is possible, how to understand it?MySQL has
1. String Case Conversion:(1). Replace all lowercase letters in the user_name field of the Tbl_student table with uppercase:Update tbl_student set User_name=upper (user_name);(2). Replace all uppercase letters in the User_name field of the
The first position of a string is labeled 1
ASCII (STR): Returns the ASCII code value of the leftmost character
CONV (N, From_base, to_base): Converts a number between different cardinality, returns a string number of number N, or null
From the database to take n fields, and then combined together with the "," split display, at first thought with CONCAT () to deal with, good is the trouble, did not expect in the manual actually mentioned Concat_ws (), very useful.
I used to mainly use the MSSQL, the recent project in the use of MySQL, oneself is a typical small white. Record a MySQL stored procedure today, where you need to split strings and execute SQL statements dynamically.About string Segmentation I began
It feels like MySQL's string function intercepts characters, and is more powerful than a program intercept (like PHP or Java), so make a record here and hope it works for everyone.Function:1. Intercept string from leftLeft (str, length)Description:
Method One:SELECT * from the users WHERE emails like "%[email protected]%";Method Two:Use the MySQL string function find_in_set ();SELECT * from Users WHERE find_in_set (' [email protected] ', emails);This is possible, how to understand it?MySQL has
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