Database Articles - Page 396 of 618

To match underscore in a MySQL string, you can use the below syntax −select *from yourTableName where yourColumnName LIKE '%\_%';Let us first create a table −mysql> create table DemoTable (    ClientId varchar(200) ); Query OK, 0 rows affected (0.79 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('CLI_101'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('CLI1110'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('_CLI102'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values('CLI103_'); Query OK, 1 row affected (0.12 sec) mysql> insert into ... Read More

To check this, you can use SHOW command. The syntax is as follows −show grants\GLet us implement the above syntax to display the permissions you have −mysql> SHOW GRANTS\GThis will produce the following output −*************************** 1. row *************************** Grants for root@%: GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, RELOAD, SHUTDOWN, PROCESS, FILE, REFERENCES, INDEX, ALTER, SHOW DATABASES, SUPER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, REPLICATION SLAVE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER, EVENT, TRIGGER, CREATE TABLESPACE, CREATE ROLE, DROP ROLE ON *.* TO `root`@`%` WITH GRANT OPTION *************************** 2. row *************************** Grants for root@%: ... Read More

In order to order by 0 first and then largest, you can use the below syntax −select *from yourTableName order by yourColumnName=0 DESC, yourColumnName DESC;Let us first create a table −mysql> create table DemoTable (    Value int ); Query OK, 0 rows affected (0.65 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(90); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(0); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(0); Query OK, 1 row affected (0.12 ... Read More

Let us first create a table −mysql> create table DemoTable (    UserId int,    UserName varchar(10),    UserAge int ); Query OK, 0 rows affected (0.73 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(101, 'Chris', 23); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(102, 'Robert', 33); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values(103, 'David', 25); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(104, 'Carol', 35); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values(105, 'Bob', 29); Query OK, ... Read More

Use MySQL JOIN to select MySQL rows where column contains same data in more than one record. Let us first create a table −mysql> create table DemoTable (    UserId int,    UserName varchar(20) ); Query OK, 0 rows affected (0.54 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(10, 'John'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(11, 'Sam'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(12, 'Larry'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(13, 'David'); Query OK, 1 row affected (0.17 ... Read More

You can use INFORMATION_SCHEMA.TABLES and AVG_ROW_LENGTH to query average row length in MySQL −SELECT AVG_ROW_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = ‘yourTableName’;Let us first create a table −mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(100) ); Query OK, 0 rows affected (0.90 sec)Insert records in the table using insert command −mysql> insert into DemoTable(StudentName) values('John'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable(StudentName) values('Larry'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable(StudentName) values('Sam'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(StudentName) values('Mike'); Query OK, ... Read More

To prevent duplicate entry, add constraint UNIQUE. Let us first create a table −mysql> create table DemoTable (    Id int,    Name varchar(100) ); Query OK, 0 rows affected (0.79 sec)Here is the query to prevent MySQL double insert using UNIQUE −mysql> alter table DemoTable add constraint id_NameUnKey UNIQUE(Id, Name); Query OK, 0 rows affected (0.82 sec) Records: 0 Duplicates: 0 Warnings: 0Insert records in the table using insert command. When we will try to the same record again, then the “Duplicate entry” error will be visible −mysql> insert into DemoTable values(11, 'John'); Query OK, 1 row affected (0.18 ... Read More

You can use LPAD() from MySQL for this. Let us first create a table −mysql> create table DemoTable (    FullName varchar(100) ); Query OK, 0 rows affected (0.81 sec)Insert records in the table using insert command −mysql> insert into DemoTable values('John Smith'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('David Miller'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Sam Williams'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('Carol Taylor'); Query OK, 1 row affected (0.47 sec)Display records from the table using select command −mysql> select *from DemoTable;This ... Read More

To select all except the first character in a string, you can use SUBSTR() method. Let us first create a table −mysql> create table DemoTable (    FirstName varchar(20) ); Query OK, 0 rows affected (0.63 sec)Insert records in the table using insert command −mysql> insert into DemoTable values('Larry'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values('Carol'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('David'); Query OK, 1 row affected (0.14 sec)Display records from the table using select command −mysql> ... Read More

You need to use backticks around the table name where the table name has blank space. Let us first create a table. Here, we have used backtick −mysql> create table `Demo Table138` (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Price int ); Query OK, 0 rows affected (0.47 sec)Insert records in the table using insert command −mysql> insert into `Demo Table138`(Price) values(450); Query OK, 1 row affected (0.18 sec) mysql> insert into `Demo Table138`(Price) values(499); Query OK, 1 row affected (0.16 sec) mysql> insert into `Demo Table138`(Price) values(199); Query OK, 1 row affected (0.17 sec) mysql> insert into ... Read More