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MySQLi Articles
Page 173 of 341
Can you check for both a blank string and 0 in one condition with a single MySQL query?
Yes, we can check for a blank string and 0 in a single condition. Let us first create a table −mysql> create table DemoTable ( ClientId varchar(40) ); Query OK, 0 rows affected (1.01 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('CLI-01'); Query OK, 1 row affected (0.36 sec) mysql> insert into DemoTable values('0'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('CLI-02'); Query OK, 1 row affected (0.31 sec) mysql> insert into DemoTable values('CLI-00'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(''); Query OK, 1 ...
Read MoreHow to collapse rows into a comma-delimited list with a single MySQL Query?
To collapse rows into a comma-delimited list, use GROUP_CONCAT(). Let us first create a table −mysql> create table DemoTable ( Id int, Name varchar(40) ); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Chris Brown'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(101, 'Adam Smith'); Query OK, 1 row affected (0.84 sec) mysql> insert into DemoTable values(101, 'John Doe'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(100, 'David Miller'); Query OK, 1 row affected (0.17 sec) mysql> insert ...
Read Moresp_help for MySQL to display field types and foreign key constraints?
In MySQL, you can achieve sp_help with the help of SHOW CREATE command.CASE 1 −For table, the syntax is as follows −SHOW CREATE TABLE yourTableName;CASE 2 −For stored procedure, the syntax is as follows −SHOW CREATE PROCEDURE yourProcedureName;Let us first create a table −mysql> create table DemoTable ( EmployeeId int NOT NULL AUTO_INCREMENT, EmployeeFirstName varchar(40) NOT NULL, EmployeeLastName varchar(40) NOT NULL, EmployeeAge int, EmployeeCountryName varchar(40), EmployeeCityName varchar(40), PRIMARY KEY(EmployeeId), UNIQUE KEY(EmployeeFirstName, EmployeeCityName) ); Query OK, 0 rows affected (0.97 sec)Let us implement the above syntax for our table −mysql> SHOW CREATE TABLE ...
Read MoreMySQL query to split the string "Learn With Ease" and return the last word?
For this, you can use SUBSTRING_INDEX(). Let us first create a table −mysql> create table DemoTable ( Words TEXT ); Query OK, 0 rows affected (1.62 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Learn With Ease'); Query OK, 1 row affected (0.32 sec) mysql> insert into DemoTable values('Intro To MySQL'); Query OK, 1 row affected (0.35 sec) mysql> insert into DemoTable values('Deep Dive Using Java'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('C++ In Depth'); Query OK, 1 row affected (0.16 sec)Display all records from the table using select ...
Read MoreSet all the columns of a MySQL table to a particular value with a single query
Let us first create a table −mysql> create table DemoTable ( ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY, ClientName varchar(40), ClientAge int, ClientCountryName varchar(40) ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ClientName, ClientAge, ClientCountryName) values('Chris', 25, 'US'); Query OK, 1 row affected (0.33 sec) mysql> insert into DemoTable(ClientName, ClientAge, ClientCountryName) values('Bob', 55, 'UK'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(ClientName, ClientAge, ClientCountryName) values('David', 45, 'AUS'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement ...
Read MoreMySQL query to make a date column NULL?
To make a date column null, use ALTER TABLE and MODIFY and set the date to NULL. Following is the syntax −alter table yourTableName modify column yourColumnName date NULL;Let us first create a table. Here, we have set the column as NOT NULL −mysql> create table DemoTable ( ShippingDate date NOT NULL ); Query OK, 0 rows affected (0.78 sec)Now, insert NULL value in the above table. An error would generate since we have set the column to be NOT NULL −mysql> insert into DemoTable values(null); ERROR 1048 (23000) − Column 'ShippingDate' cannot be nullNow, let us alter the ...
Read MoreWhat is the syntax in MySQL to get the column names of a table?
The syntax is as follows to get the column names of a table −select column_name from information_schema.columns where table_schema='yourDatabaseName' and table_name=’yourTableName’;Let us first create a table −mysql> create table DemoTable ( EmployeeId int, EmployeeFirstName varchar(20), EmployeeLastName varchar(20), EmployeeAge int, EmployeeCountryName varchar(40), IsMarried tinyint(1), isActive ENUM('ACTIVE', 'INACTIVE') ); Query OK, 0 rows affected (0.65 sec)Following is the query to get the column names of a table. Here, we are fetching the column names of DemoTable −mysql> select column_name from information_schema.columns where table_schema='web' and table_name='DemoTable';This will produce the following output −+---------------------+ | ...
Read MoreCheck if a field of table has NOT NULL property set in SQL?
To check if field of a table has NOT NULL property, you can use any of the two syntaxes. The first syntax is as follows −desc yourTableName;Following is the second syntax −select column_name, is_nullable from information_schema.columns where table_schema = ‘yourDatabaseName’ and table_name = 'yourTableName’;Let us first see an example and create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(40), StudentAge int NOT NULL, IsActiveStudent ENUM('ACTIVE", INACTIVE') NOT NULL, StudentCountryName varchar(40) ); Query OK, 0 rows affected (1.53 sec)The first syntax is as follows ...
Read MorePrevent a combination of items from being inserted twice in MySQL?
To prevent a combination of items from being inserted twice, alter the table and set UNIQUE for the column as shown in the below syntax −alter table yourTableName add constraint yourConstraintName unique(yourColumnName1, yourColumnName2, ....N);Let us first create a table −mysql> create table DemoTable ( Value1 int, Value2 int ); Query OK, 0 rows affected (0.47 sec)Here is the query to prevent a combination of items from being inserted twice −mysql> alter table DemoTable add constraint Value1_Value2_ConstraintKey unique(Value1, Value2); Query OK, 0 rows affected (0.80 sec) Records : 0 Duplicates : 0 Warnings : 0Insert some records in the ...
Read MoreFind integer within +/- 1 from a column in MySQL
For this, use BETWEEN -1 AND 1. Let us first create a table −mysql> create table DemoTable ( Value int ); Query OK, 0 rows affected (0.76 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(14); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(15); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(16); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(17); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable values(18); Query OK, 1 row affected (0.09 sec)Display all records from ...
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