Database Articles - Page 503 of 546

MySQL INSERT() function performs no insertion if the position of insertion is not within the length of the string. There are certain cases like we pass a negative or 0(zero) value or the value goes beyond the value of a total number of characters in an original string by 2 when we can say that ‘pos’ is not within the length of the string. It can be understood with the help of the following example −ExampleThe query below will perform no insertion because the ‘pos’ is not within the length of string i.e. a negative value.mysql> Select INSERT('Tutorialspoint', -1, 4, '.com'); +--------------------------------------+ ... Read More

We can use a MySQL INSERT() function to insert a substring at the specified position in a string.SyntaxINSERT(original_string, @pos, @len, new_string)Here, original_string is the string in which we want to insert a new string at the place of some specific number of characters.@pos is the position at which the insertion of the new string should start.@len is the number of characters that should delete from the original string. The starting point of the deletion of characters is the value of @pos.New_string is the string we want to insert into the original string.Examplemysql> Select INSERT('MySQL Tutorial', 7, 8, '@Tutorialspoint'); +------------------------------------------------+ | ... Read More

We can use the keyword USING to produce a string, other than default binary string, in a given character set. Following result set will demonstrate it −mysql> Select CHARSET(CHAR(85 USING utf8)); +------------------------------+ | CHARSET(CHAR(85 USING utf8)) | +------------------------------+ | utf8                         | +------------------------------+ 1 row in set (0.00 sec)The above result set shows that the returned binary string is utf8 because we write utf8 after the keyword USING.mysql> Select CHARSET(CHAR(85 USING latin1)); +--------------------------------+ | CHARSET(CHAR(85 USING latin1)) | +--------------------------------+ | latin1                 ... Read More

With the help of CHARSET() function, we can check which string is returned by MySQL CHAR() function. Following result set will demonstrate it − mysql> Select CHARSET(CHAR(85)); +-------------------+ | CHARSET(CHAR(85)) | +-------------------+ | binary | +-------------------+ 1 row in set (0.00 sec)

MySQL converts the arguments of CHAR() function which is greater than 255 to multiple result bytes. For example, CHAR(260) is equivalent to CHAR(0,1,0,4). It can be more clear with the help of following statements −mysql> Select HEX(CHAR(256)),HEX(CHAR(1,0)); +----------------+----------------+ | HEX(CHAR(256)) | HEX(CHAR(1,0)) | +----------------+----------------+ | 0100           | 0100           | +----------------+----------------+ 1 row in set (0.00 sec)The above result set shows that CHAR(256) is equivalent to CHAR(1,0).

MySQL CHAR() function will ignore NULL if it is provided as an argument to it. To understand it, consider the following examples −mysql> Select CHAR(65,66,67,NULL); +---------------------+ | CHAR(65,66,67,NULL) | +---------------------+ | ABC                 | +---------------------+ 1 row in set (0.00 sec) mysql> Select CHAR(NULL,66,67,NULL); +-----------------------+ | CHAR(NULL,66,67,NULL) | +-----------------------+ | BC                    | +-----------------------+ 1 row in set (0.00 sec)In both the examples above, CHAR() function ignores the NULL and converts the numeric value into character value.

MySQL IF ELSE statement implements a basic conditional construct when the expression evaluates to false. Its syntax is as follows −IF expression THEN    statements; ELSE    else-statements; END IF;The statements must end with a semicolon.To demonstrate the use of IF ELSE statement within MySQL stored procedure, we are creating the following stored procedure which is based on the values, as shown below, of the table named ‘student_info’ −mysql> Select * from student_info; +------+---------+------------+------------+ | id   | Name    | Address    | Subject    | +------+---------+------------+------------+ | 101  | YashPal | Amritsar   | History    | | 105  | ... Read More

The IGNORE_SPACE SQL mode can be used to modify how the parser treats function names that are whitespace-sensitive. Following are the cases in which we can use IGNORE_SPACE SQL mode −Case-1  − When IGNORE_SPACE SQL mode is disabledAfter disabling the IGNORE_SPACE SQL mode, the parser interprets the name as a function call when there is no whitespace between the name and the following parenthesis. This also occurs when the function name is used in a non-expression context. It can be understood from the following query −mysql> Create table SUM(Id Int); ERROR 1064 (42000): You have an error in your SQL ... Read More

Actually, when a parser encounters a word that is the name of a built-in function, it must determine whether the name represents a function call or is instead a non-expression reference to an identifier such as a table or column name. consider the following queries −1. Select sum(salary) from employee; 2. Create table sum (i int);In the first query SUM is a reference to a function call and in the second query, it is referencing to table name.Parser follows the following rules to distinguish whether their names are being used as function calls or as identifiers in non-reference context −Rule1 ... Read More

MySQL SUBSTRING_INDEX() function will return the same string as output if the argument ‘count’ has the value greater than the total number of occurrences of delimiter. It can be demonstrated with the following example −mysql> Select SUBSTRING_INDEX('My Name is Ram','a',3); +-----------------------------------------+ | SUBSTRING_INDEX('My Name is Ram','a',3) | +-----------------------------------------+ | My Name is Ram                          | +-----------------------------------------+ 1 row in set (0.00 sec)The above query returns the same string because 3 is greater than the total number of occurrences of delimiter provided as argument i.e. ‘a’. There are only two ‘a’ in the string.