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MySQLi Articles
Page 29 of 341
Is it impossible to add a column in MySQL specifically before another column?
No, you can easily add a column before another column using ALTER.Note − To add a column at a specific position within a table row, use FIRST or AFTER col_name Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20), -> CountryName varchar(100) -> ); Query OK, 0 rows affected (0.67 sec)Let us check all the column names from the table −mysql> show columns from DemoTable;OutputThis will produce the following output −+-------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key ...
Read MoreMySQL XOR operator with IN clause?
MySQL XOR returns TRUE if one or the other operand (or expression) but not both is TRUE. The IN clause is used to specify a condition with any other MySQL query.Let us first create a tablemysql> create table DemoTable -> ( -> Num1 int, -> Num2 int -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(5, 5); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(6, 6); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(7, 7); Query OK, ...
Read MoreCan we use ORDER BY NULL in MySQL?
Yes, we can do thatNote − Before MySQL 5.7, ORDER BY NULL was useful, but with MySQL 8.0, specifying ORDER BY NULL, for example, at the end to suppress implicit sorting is no longer necessary.Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(10) -> ); Query OK, 0 rows affected (1.01 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Bob'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('David'); Query OK, 1 ...
Read MoreSort a column in descending order after placing argument in MySQL IN()?
For this, use FIELD() function with DESC. Let us first create a table −mysql> create table DemoTable -> ( -> Number int -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(40); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(50); Query OK, 1 row ...
Read MoreDisplay records from two columns based on comparison in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Num1 int, -> Num2 int -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 200); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(200, 100); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(300, 400); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(400, 300); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(500, 600); Query OK, 1 ...
Read MoreCount only null values in two different columns and display in one MySQL select statement?
Use IS NULL to test for NULL value. Let us first create a table −mysql> create table DemoTable -> ( -> Number1 int, -> Number2 int -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(1, NULL); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(NULL, NULL); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(3, NULL); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(NULL, 90); Query OK, 1 row affected ...
Read MoreMySQL query to remove special characters from column values?
Let us first create a table −mysql> create table DemoTable -> ( -> StudentId varchar(100) -> ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('STU#123'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('STU#567'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('STU#98494'); Query OK, 1 row affected (0.19 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-----------+ | StudentId | +-----------+ | STU#123 | | STU#567 ...
Read MoreChange multiple columns in a single MySQL query?
For this, use UPDATE and REPLACE() in MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(100), -> StudentCountryName varchar(100) -> ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentName, StudentCountryName) values('John', 'US'); Query OK, 1 row affected (0.15 sec)Display all records from the table using select statement −mysql select *from DemoTable;OutputThis will produce the following output −+-----------+-------------+--------------------+ | StudentId | StudentName | StudentCountryName | +-----------+-------------+--------------------+ | ...
Read MoreHow to set a string with hyphen and numbers in MySQL varchar?
To set a string with hyphen and numbers, you need to use single quotes. For example, 'Customer-1234-899', 'Customer-9383-901', etc.Let us first create a table −mysql> create table DemoTable -> ( -> CustomerId varchar(100) -> ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Customer-1234-899'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Customer-8373-900'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Customer-9383-901'); Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −mysql> select *from DemoTableOutputThis ...
Read MoreExtract the middle part of column values in MySQL surrounded with hyphens and display in a new column?
Use the SUBSTR() method to extract the middle part of column values surrounded with hyphens, for example, “11-84848-11”.Let us first create a table −mysql> create table DemoTable -> ( -> Number varchar(100), -> Number1 varchar(100) -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Number) values('11-84848-11'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(Number) values('22-99999-22'); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-------------+---------+ | Number ...
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