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Database Articles
Page 229 of 547
Count 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 ...
Read MoreConvert hex string to number in MySQL?
Use the CONV() method to convert hex string to number −select CONV(yourColumnName, 16, 10) AS anyAliasName from yourTableName;Let us first create a table −mysql> create table DemoTable -> ( -> HexString varchar(100) -> ); Query OK, 0 rows affected (0.82 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('A'); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable values('F'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('B'); Query OK, 1 row affected (0.55 sec) mysql> insert into DemoTable values('ABC'); Query OK, 1 row affected (0.11 sec)Display ...
Read MoreMySQL query to display a substring before a special character in a string
Use the LOCATE() and SUBSTRING() method for this in MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> Title text -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Introduction To Java'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Introduction - To MySQL'); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-------------------------+ | Title ...
Read MoreGet the substring of a column in MySQL
Use the SUBSTR() method to get the substring of a column.Let us first create a table −mysql> create table DemoTable -> ( -> Title text -> ); Query OK, 0 rows affected (0.74 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('This is a MySQL Database'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('Java is an Object Oriented Programming Language'); Query OK, 1 row affected (0.17 sec)Display all records from the table using select statement −mysql> select *from DemoTable ;OutputThis will produce the following output −+-------------------------------------------------+ | Title ...
Read MoreDiscard last 3 characters of a field in MySQL
Let us first create a table −mysql> create table DemoTable -> ( -> StudentId varchar(100) -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('STU-090'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('STU-123'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('STU-678'); Query OK, 1 row affected (0.29 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-----------+ | StudentId | +-----------+ | STU-090 | ...
Read MoreComparing two columns in a single MySQL query to get one row?
For this, you can use ORDER BY clause. Let us first create a table −mysql> 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(60, 249); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(59, 250); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+------+------+ | Num1 | Num2 | +------+------+ | 60 | 249 ...
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