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Database Articles
Page 378 of 547
What 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 ...
Read MoreFetch records from interval of past 3 days from current date in MySQL and add the corresponding records
Let us first create a table −mysql> create table DemoTable ( ProductAmount int, PurchaseDate datetime ); Query OK, 0 rows affected (0.94 sec)Note − Let’s say the current date is 2010-09-15.Insert some records in the table using insert command −mysql> insert into DemoTable values(567, '2019-09-10'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(1347, '2019-09-14'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(2033, '2019-09-13'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(1256, '2019-09-11'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values(1000, '2019-09-16'); Query ...
Read MoreMySQL query for text search with LIKE and OR to fetch records
Let us first create a table −mysql> create table DemoTable ( Subject text ); Query OK, 0 rows affected (0.86 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Introduction to MySQL'); Query OK, 1 row affected (0.31 sec) mysql> insert into DemoTable values('Deep Dive using Java'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('C in Depth'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Introduction to C++'); Query OK, 1 row affected (0.48 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will ...
Read MoreHow to select a query for a selected day(2010-11-04) to current date using MySQL?
Let us first create a table −mysql> create table DemoTable ( Joiningdate date ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2010-01-01'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('2010-03-31'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('2010-11-04'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('2012-12-31'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('2019-01-03'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('2016-04-05'); Query OK, 1 row affected ...
Read MoreCompare date when the AdmissionDate is less than the current date in MySQL
Let us first create a table −mysql> create table DemoTable ( AdmissionDate varchar(50) ); Query OK, 0 rows affected (0.63 sec)Note − Let’s say the current date is 14-Sep-2019.Insert some records in the table using insert command. Following is the query −mysql> insert into DemoTable values('15-Sep-2019'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('14-Sep-2019'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('13-Sep-2016'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('13-Sep-2019'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('13-Sep-2020'); Query OK, 1 row affected ...
Read MoreCan we implement nested insert with select in MySQL?
Yes, we can implement nested insert with select in MySQL as shown in the below syntax −insert into yourTableName2(yourColumnName1, yourColumnName2, .....N) select yourColumnName1, yourColumnName2, ....N from yourTableName1 where yourCondition;Let us first see an example and create a table −mysql> create table DemoTable1 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(40) ); Query OK, 0 rows affected (0.88 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1(Name) values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1(Name) values('David'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1(Name) values('Bob'); Query ...
Read MoreMySQL CASE WHEN with SELECT to display odd and even ids?
Let us first create a table −mysql> create table DemoTable ( PageId int ); Query OK, 0 rows affected (0.85 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(233); Query OK, 1 row affected (0.36 sec) mysql> insert into DemoTable values(34); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(76); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(89); Query OK, 1 row affected (0.26 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+--------+ | PageId | +--------+ ...
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