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Database Articles
Page 526 of 547
Selecting a single row in MySQL?
If you want to select a single row on the basis of primary key, use the WHERE clause. The syntax is as follows −SELECT * FROM yourTableName WHERE yourPrimaryKeyColumnName = someValue;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectWithPrimaryKey -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(20), -> Age int, -> Marks int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command. The query is ...
Read MoreIs there a way in MySQL to reverse a boolean field with a single query?
Yes, you can use if() function from MySQL to reverse a boolean field. The syntax is as follows −UPDATE yourTableName SET yourBooleanColumnName = IF(yourBooleanColumnName, 0, 1);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table ReverseBooleanField -> ( -> Id int NOT NULL AUTO_INCREMENT, -> isValid BOOLEAN -> , -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.56 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into ReverseBooleanField(isValid) values(true); ...
Read MoreSum values of a single row in MySQL?
You can use below syntax to sum values of a single row −Case 1 − The following is the syntax if your column does not have NULL value −SELECT yourColumnName1+yourColumnName2+yourColumnName3+.......+N as anyVariableName FROM yourTableName;Case 2 − If your column has NULL value then use this syntax −SELECT IFNULL(yourColumnName1, 0)+ IFNULL(yourColumnName2, 0)+ IFNULL(yourColumnName3, 0)+.............+N AS anyVariableName FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table SumValueOfSingleRow -> ( -> Id int NOT NULL AUTO_INCREMENT, -> FirstValue int, -> SecondValue int, -> ThirdValue ...
Read MoreHow to quote values using MySQL group_concat?
You can quote values using concat() and grop_concat() function from MySQL. The syntax is as follows −SELECT GROUP_CONCAT(CONCAT(' '' ', yourColumnName, ' '' ' )) as anyVariableName from yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table Group_ConcatDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Value int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (1.56 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into Group_ConcatDemo(Value) ...
Read MoreMySQL Query a List of Values?
To query a list of values, you can use IN operator. The syntax is as follows −SELECT * FROM yourTableName WHERE yourColumnName IN(Value1, Value2, ...N) ORDER BY FIELD(yourColumnName, Value1, Value2, ...N);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table ListOfValues -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(30), -> Age int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert ...
Read MoreHow do I pass a variable to a MySQL script?
You can pass a variable to a MySQL script using session variable. First you need to set a session variable using SET command. After that you need to pass that variable to a MySQL script.The syntax is as follows −First Step: Use of Set command.SET @anyVariableName − = ’yourValue’;Second Step: Pass a variable to a MySQL script.UPDATE yourTableName SET yourColumnName1 = yourColumnName1+integerValue WHERE yourColumnName2 = @anyVariableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table Employee_Information -> ( -> EmployeeId int NOT NULL AUTO_INCREMENT, -> ...
Read MorePerforming a MySQL LIKE comparison on an INT field?
You need to use cast() method to perform comparison on an INT field. The syntax is as follows −SELECT yourColumnName1, yourColumnName2, ......N yourTableName WHERE CAST(yourColumnName as CHAR) LIKE ‘%yourIntegerValue%’;To understand the above syntax, let us create a table. The following is the query to create a table for performing a LIKE comparison on INT field −mysql> create table ComparisonOnIntField -> ( -> StudentId int NOT NULL, -> StudentName varchar(20), -> StudentAge int -> ); Query OK, 0 rows affected (1.00 sec)Insert some records in the table to perform a MySQL LIKE comparison on an INT ...
Read MoreFind lowest Date (custom) in MySQL?
To find lowest Date(custom) in MySQL, let us first create a table. The query to create a table is as follows:mysql> create table FindMinimumDate -> ( -> Id int NOT NULL AUTO_INCREMENT, -> yourDay varchar(2), -> yourMonth varchar(2), -> yourYear varchar(4), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command. The query is as follows:mysql> insert into FindMinimumDate(yourDay, yourMonth, yourYear) values('21', '11', '2019'); Query OK, 1 row affected (0.10 sec) mysql> insert into FindMinimumDate(yourDay, yourMonth, yourYear) values('20', '10', '2020'); Query OK, ...
Read MoreWhy the G modifier in SELECT * FROM table_nameG?
The \G modifier gets the result in vertical order. If you use \g modifier, then it won’t affect the result. The \g works likesemi-colon.Let us first create a table. The query to create a table is as follows:mysql> create table DemoOfVertical -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(20), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (3.40 sec)Now you can insert some records in the table using insert command. The query is as follows:mysql> insert into DemoOfVertical(Name) values('Bob'); Query OK, 1 row affected (0.18 sec) mysql> insert into ...
Read MoreWhat is the limit of auto_increment (integer) in MySQL?
The limit of auto_increment integer depends on column data type. Displayed as follows:The data type TINYINT range is 127 The data type UNSIGNED TINYINT range is 255 The data type SMALLINT range is 32767 The data type UNSIGNED SMALLINT range is 65535 The data type MEDIUMINT range is 8388607 The data type UNSIGNED MEDIUMINT range is 16777215 The data type INT range is 2147483647 The data type UNSIGNED INT range is 4294967295 The data type BIGINT range is 9223372036854775807 The data type UNSIGNED BIGINT range is 18446744073709551615Let us take an example of TINYINT. If you will give beyond 127, then ...
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