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Articles by karthikeya Boyini
Page 131 of 143
The best data type to store 0, 1, null values in MySQL?
You need to use tinyint(1) unsigned NULL to store the value 0, 1 and null values. The syntax is as follows −yourColumnName TINYINT(1) UNSIGNED NULL;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table StoreValue0and1orNULLDemo -> ( -> isDigit TINYINT(1) UNSIGNED NULL -> ); Query OK, 0 rows affected (0.63 sec)Now you can insert records 0, 1, and NULL in the table using insert command. The query is as follows −mysql> insert into StoreValue0and1orNULLDemo values(0); Query OK, 1 row ...
Read MoreDoes MySQL eliminate common subexpressions between SELECT and HAVING/GROUP BY clause? How to test it?
To test, use the sleep() function.Case 1 −The syntax is as follows −SELECT yourColumnName+sleep(yourIntegerValue) FROM yourTableName GROUP BY yourColumnName+sleep(yourIntegerValue);;Case 2 − You can use another syntax which is as follows −SELECT yourColumnName+sleep(yourIntegerValue) As anyAliasName FROM yourTableName GROUP BY yourAliasName;To understand the above syntaxes, let us create a table. The query to create a table is as follows −mysql> create table sleepDemo -> ( -> value int -> ); Query OK, 0 rows affected (1.25 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into sleepDemo values(40); Query OK, 1 row ...
Read MoreMultiple Inserts for a single column in MySQL?
The syntax for multiple inserts for a single column in MySQL is as follows −INSERT INTO yourTableName(yourColumnName) values(‘yourValue1'), (‘yourValue2'), (‘yourValue3'), (‘yourValue4'), .........N;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table InsertMultipleDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserName varchar(10), -> UserRole varchar(20) -> , -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (3.14 sec)Now you can insert some records in the ...
Read MoreJavaTuples setAt2() method for Septet class
The setAt2() method is used to set the Septet value in JavaTuples and a copy with a new value at the specified index i.e. index 2 here.Let us first see what we need to work with JavaTuples. To work with Septet class in JavaTuples, you need to import the following package −import org.javatuples.Septet;Note − Steps to download and run JavaTuples program If you are using Eclipse IDE to run Septet Class in JavaTuples, then Right Click Project → Properties → Java Build Path → Add External Jars and upload the downloaded JavaTuples jar file.The following is an example −Exampleimport org.javatuples.Septet; ...
Read MoreMySQL select dates in 30-day range?
To select dates in 30-day range, you can use arithmetic operation - with interval.The syntax is as follows −select *from yourTableName where yourDateColumnName > NOW() - INTERVAL 30 DAY and yourDateColumnName < NOW() + INTERVAL 30 DAY;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectDatesDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ArrivalDate datetime -> ); Query OK, 0 rows affected (0.77 sec)Now you can insert some records in the table using insert command. The query is as ...
Read MoreHow to remove hyphens using MySQL UPDATE?
To remove hyphens using MySQL update, you can use replace() function. The syntax is as follows −update yourTableName set yourColumnName=replace(yourColumnName, '-', '' );To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table removeHyphensDemo -> ( -> userId varchar(100) -> ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into removeHyphensDemo values('John-123-456'); Query OK, 1 row affected (0.22 sec) mysql> insert into removeHyphensDemo values('Carol-9999-7777-66555'); Query OK, 1 row affected (0.19 sec) ...
Read MoreMySQL select order by acts like a string (not a number)?
You can use the following syntax if your column has varchar data type −select yourColumnName FROM yourTableName ORDER BY yourColumnName +0 DESC;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectOrderdemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(100), -> RankNumber varchar(100) -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into selectOrderdemo(Name, RankNumber) values('Larry', -100); Query OK, 1 row affected (0.23 ...
Read MoreMySQL Merge selects together?
To merge selects together, you need to use GROUP BY clause. To understand the concept, let us create a table. The query to create a table is as follows −mysql> create table MergingSelectDemo -> ( -> RoomServicesId int, -> RoomId int, -> ServiceId int -> ); Query OK, 0 rows affected (1.98 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into MergingSelectDemo values(10, 10, 10); Query OK, 1 row affected (0.29 sec) mysql> insert into MergingSelectDemo values(20, 10, 20); Query OK, 1 row affected ...
Read MoreHow to copy data from one field to another on every row in MySQL?
To copy data from one field to another on every row, use the UPDATE command.Let us first create a table −mysql> create table DemoTable ( StudentId int, StudentFirstName varchar(20), StudentMarks int default 0 ); Query OK, 0 rows affected (0.49 sec)Following is the query to insert records in the table using insert command −mysql> insert into DemoTable(StudentId, StudentFirstName) values(89, 'Larry'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentId, StudentFirstName) values(35, 'Robert'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(StudentId, StudentFirstName) values(48, 'Chris'); Query OK, 1 row affected (0.13 sec) ...
Read MoreROW_NUMBER() equivalent in MySQL for inserting?
There is no equivalent of ROW_NUMBER() in MySQL for inserting but you can achieve this with the help of variable. The syntax is as follows −SELECT (@yourVariableName:=@yourVariableName + 1) AS `anyAliasName`, yourColumnName1, yourColumnName2, ...N FROM yourTableName ,(SELECT @yourVariableName:=0) AS anyAliasName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table RowNumberDemo -> ( -> UserId int, -> UserName varchar(20) -> ); Query OK, 0 rows affected (0.74 sec)Insert some records in the table using insert command. The ...
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