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MySQLi Articles
Page 74 of 341
What are the default rules used by the parser for parsing names of built-in functions?
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 MoreWhat is the use of IGNORE_SPACE SQL mode?
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 MoreHow MySQL IF ELSE statement can be used in a stored procedure?
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 MoreHow can I create a stored procedure to select values on the basis of some conditions from a MySQL table?
We can create a stored procedure with IN and OUT operators to SELECT records, based on some conditions, from MySQL table. To make it understand we are taking an example of a table named ‘student_info’ having the following data −mysql> Select * from student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Jaipur | Literature | | 110 | Rahul | Chandigarh | History | | 125 | Raman | Bangalore | ...
Read MoreIn MySQL, what is Bit-field notation and how it can be used to write bit-field value?
Bit-field notation is the notation with the help of which we can write bit-field values. The syntax of Bit-field notation is as follows −Syntaxb’value’ OR 0bvalueHere, the value is a binary value written by using zeros and ones.The mainly Bit-filed notation is convenient for specifying values to be assigned to BIT columns of MySQL table. Following example will demonstrate it −mysql> Create table bit_testing (bittest BIT(8)); Query OK, 0 rows affected (1.09 sec) mysql> INSERT INTO bit_testing SET bittest = b'10101010'; Query OK, 1 row affected (0.07 sec) mysql> INSERT INTO bit_testing SET bittest = b'0101'; Query ...
Read MoreWhat is the default type of a bit value assigned to user variables?
By default, the bit values assigned to the user variables are binary strings. It can be illustrated by assigning the bit value to a user variable and then by retrieving them as follows −mysql> SET @abc = 0b1000011; Query OK, 0 rows affected (0.00 sec) mysql> Select @abc; +------+ | @abc | +------+ | C | +------+ 1 row in set (0.00 sec)The above result set shows that the default type of a bit value assigned to user variables are binary strings.
Read MoreHow can we display MySQL bit values in printable form?
Actually, Bit values are returned as binary values but we can also display them in the printable form with the help of following −By adding 0We can display Bit values in printable form by adding 0 to them. Following the example from the bit_testing table can be used to understand it −mysql> Select bittest+0 from bit_testing; +-----------+ | bittest+0 | +-----------+ | 170 | | 5 | | 5 | +-----------+ 3 rows in set (0.00 sec)By using conversion function BIN(), OCT(), HEX()We can also display Bit values in ...
Read MoreHow can I create a stored procedure to delete values from a MySQL table?
We can create a stored procedure with IN operator to delete values from a MySQL table. To make it understand we are taking an example of a table named ‘student_info’ having the following data −mysql> Select * from student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 100 | Aarav | Delhi | Computers | | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Jaipur | Literature | | 110 | Rahul | Chandigarh | History | +------+---------+------------+------------+ ...
Read MoreHow can I create a stored procedure to update values in a MySQL table?
We can create a stored procedure with IN operator to update values in a MySQL table. To make it understand we are taking an example of a table named ‘student_info’ having the following data −mysql> Select * from student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Jaipur | Literature | | 110 | Rahul | Chandigarh | History | | 125 | Raman | Bangalore | Computers | +------+---------+------------+------------+ 4 rows ...
Read MoreHow can we assign a bit value as a number to a user variable?
As we know that the default type of a bit values assigned to user variables is binary strings but we can also assign a bit value to a number by using the following two methods −By using CAST() functionWith the help of CAST(… AS UNSIGNED) the bit value can be assigned a number. The following example will illustrate it −mysql> SET @abc = CAST(0b1000011 AS UNSIGNED); Query OK, 0 rows affected (0.00 sec) mysql> Select @abc; +------+ | @abc | +------+ | 67 | +------+ 1 row in set (0.00 sec)By adding 0(+0)The bit value can be assigned ...
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