As we know that certain objects within MySQL are known as identifiers. These objects include a database, table, index, column, alias, view, stored procedure, partition, tablespace etc. Identifiers are stored using Unicode (UTF-8). The maximum length of each type of identifier is given in the following table:Sr. No.IdentifierMaximum Length (characters)1Database642Table643Column644Index645Constraint646Stored Procedure or Function647Trigger648View649Event6410Tablespace6411Log File Group6412Alias25613Compound Statement Label16

We must have to use quotes with reserved words to use them as an identifier. The quotes can be single or double depends upon ANSI_QUOTES SQL mode.If this mode is disabled then the identifier quote character is the backtick (“`”). Consider the following example in which we created a table named ‘select’ −mysql> create table `select`(id int); Query OK, 0 rows affected (0.19 sec)If this mode is enabled then we can use backtick (“`”) and double quotes (“”) both as identifier quote character. Consider the following example in which we created a table named ‘trigger’ −mysql> Create table "trigger" (id ... Read More

In MySQL, it is not possible that a client can hold user variable permanently. It is because all the variables for a given client connection are automatically freed when that client exits.

In MySQL, a user-defined variable defined by one client cannot be seen or used by another client because user-defined variables are connection-specific. It means that all variables for a given client connection are automatically freed when that client exits

MySQL allows us to use integer values as the arguments of the LOCATE() function. We do not need to use quotes. It can be demonstrated with the help of the following example −Examplemysql> Select LOCATE(5,1698235); +-------------------+ | LOCATE(5,1698235) | +-------------------+ |                 7 | +-------------------+ 1 row in set (0.00 sec) mysql> Select LOCATE(56,1698235); +--------------------+ | LOCATE(56,1698235) | +--------------------+ |                  0 | +--------------------+ 1 row in set (0.00 sec) mysql> Select LOCATE(23,1698235); +--------------------+ | LOCATE(23,1698235) | +--------------------+ |                  5 | +--------------------+ 1 row in set (0.00 sec)

On the basis of the working of both the functions, we can say that both are the complement of each other. Actually, as we know that FIELD() function, on providing a string as an argument, returns the index number of the string from string list and ELT() function, on providing index number as an argument, returns the string from string list. In the following example, we have applied both the functions on the same string, it would demonstrate the concept −Examplemysql> SELECT ELT(4, 'Ram', 'is', 'good', 'boy')As Result; +--------+ | Result | +--------+ | boy    | +--------+ ... Read More

We can store a value in a user-defined variable in a statement and then refer to it afterward in other statements. Followings are the ways to store a value in user-defined variable −With SET statementwe can store a user-defined variable by issuing a SET statement as follows −SyntaxSET @var_name = expr[, @var_name = expr]…In this @var_name is the variable name which consists of alphanumeric characters from current character set. We can use either = or := assignment operator with SET statement.For example following queries can store the user variables with SET statement −mysql> SET @value = 500; Query OK, 0 ... Read More

As we know that the default value of the fifth argument i.e. number of bits is 64, hence if we will not specify any value on fifth argument them MySQL will check the bits up to 64 bits and produce the result. Whereas, on skipping the fourth argument i.e. separator, MySQL will use a comma (, ) as a separator while displaying the output.Examplemysql> SELECT EXPORT_SET(8, 'Y', 'N')\G *************************** 1. row *************************** EXPORT_SET(8, 'Y', 'N'): N, N, N, Y, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, ... Read More

Actually, the default value of the fifth argument i.e. number of bits is 64, hence if we will not specify any value on fifth argument them MySQL will check the bits up to 64 bits and produce the result. It can be understood from the following example −Examplemysql> SELECT EXPORT_SET(5, 'Y', 'N', ' ')\G *************************** 1. row *************************** EXPORT_SET(5, 'Y', 'N', ' '): Y N Y N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N ... Read More

When designing a database, setting default values for certain fields will improve data integrity. In MySQL, ENUM data type allows you to specify predefined values for a column such as status (complete or incomplete). This article helps you to set a default value for ENUM columns, to ensure that even if the data is missing, a suitable value is automatically assigned. Inserting a default value with ENUM data type We can do this with the help of the DEFAULT attribute of the ENUM data type. The DEFAULT attribute causes an ENUM data type to have a default value when a ... Read More