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Technical articles with clear explanations and examples
MySQL query to display structure of a table
To display structure of a table, following is the syntax −show create table yourTableName;Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EmployeeFirstName varchar(100), -> EmployeeLastName varchar(100), -> EmployeeAge int, -> isMarried tinyint(1), -> EmployeeAddress varchar(100), -> EmployeeCountryName varchar(100) -> ); Query OK, 0 rows affected (0.62 sec)Here is the query to display structure −mysql> show create table DemoTable;OutputThis will produce the following output −+--------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table ...
Read MoreMultiple column sorting in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Value int -> ); Query OK, 0 rows affected (0.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 85885); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(101, 885995474); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(100, 895943); Query OK, 1 row affected (0.20 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+------+-----------+ | Id ...
Read MoreHow do I multiply an unsigned int by -1 on a MySQL SELECT?
Let us first create a table −mysql> create table DemoTable -> ( -> Value int -> ); Query OK, 0 rows affected (0.80 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(100); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-------+ | Value | +-------+ | 10 | | ...
Read MoreOrder by number of chars in MySQL?
To order by number of chars, use ORDER BY and LENGTH() method. Following is the syntax −select *from yourTableName order by LENGTH(yourColumnName) DESC;Let us first create a table −mysql− create table DemoTable -> ( -> Name varchar(100) -> ); Query OK, 0 rows affected (0.50 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('Bob'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable ...
Read MoreHow to concatenate MySQL distinct query results into a string?
Use group_concat() function from MySQL to concatenate. Let us first create a table −mysql> create table DemoTable -> ( -> Subject varchar(10) -> ); Query OK, 0 rows affected (0.43 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('C'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('C++'); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable values('C++'); Query OK, 1 row affected (0.06 sec) mysql> insert into DemoTable values('MongoDB'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('MySQL'); Query ...
Read MoreGet only digits using regexp in MySQL?
If you want to get only digits using REGEXP, use the following regular expression( ^[0-9]*$) in where clause.Case 1 − If you want only those rows which have exactly 10 digits and all must be only digit, use the below regular expression.SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[0-9]{10}$';Case 2 − If you want only those rows with the digit either 1 or more, the following is the syntax −SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[0-9]*$';The above syntax will give only those rows that do not have any any characters.To understand the above syntax, let us create a table. The query ...
Read MoreFetch rows where first character is not alphanumeric in MySQL?
To fetch rows where first character is not alphanumeric, you can use the following regular expression.Case 1 − If you want those rows that starts from a digit, you can use the following syntax −SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[0-9]';Case 2 − If you want those rows that start from an alphanumeric, use the following syntax −SELECT *FROM yourTableName WHERE yourColumnName REGEXP '^[^0-9A-Za-z]' ;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table getRowsFirstNotAlphanumeric -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserPassword varchar(20), -> PRIMARY ...
Read MoreHow to update data in a MySQL database without removing the old data?
For this, you can use UPDATE and concatenate the new data with the old one to save the old data as well −update yourTableName set yourColumnName=concat(yourColumnName, ", yourValue");Let us first create a table −mysql> create table DemoTable -> ( -> CustomerName varchar(100) -> ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('Sam'); Query OK, 1 row affected (0.14 sec)Display all records from ...
Read MoreGet part of a string based on a character in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Code varchar(100) -> ); Query OK, 0 rows affected (1.07 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('/101/102/106'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('/110/111/101'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('/111/114/201'); Query OK, 1 row affected (0.47 sec) mysql> insert into DemoTable values('/111/118'); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce ...
Read MoreHow to open MySQL command line on Windows10?
To open the MySQL command line from cmd, you need to use username root with your password.Follow the below given steps. The syntax is as follows −cd \> press enter key cd Program Files\MySQL\MySQL Server 8.0\bin> press enter key C:\Program Files\MySQL\MySQL Server 8.0\bin>mysql -uroot -p press enter key Enter password: ******Here is the step by step instruction to open MySQL command line. First, Go to START > RUN or Open Run using Windows+R command −Type CMD and hit OK button −After pressing OK button, the CMD will open −Now you need to follow the above instruction. First reach your bin ...
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