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MySQL Articles
Page 319 of 355
Calculate age based on date of birth in MySQL?
Calculate Age based on date of birth with the help of DATE_FORMAT() method in MySQL. Firstly, get the current date time with the help of now() method and you can place your date of birth in DATE_FORMAT().The syntax is as follows −SELECT DATE_FORMAT(FROM_DAYS(DATEDIFF(now(), 'yourDateofbirth')), '%Y')+0 AS anyVariableName;Apply the above syntax to calculate age from yourDateofbirth. In the above syntax, replace yourDateofbirth with your date of birth. The query is as follows −SELECT DATE_FORMAT(FROM_DAYS(DATEDIFF(now(), '2010-11-25')), '%Y')+0 AS Age;The following is the output −+------+ | Age | +------+ | 8 | +------+ 1 row in set (0.00 sec)Let ...
Read MoreHow to change the default charset of a MySQL table?
To change the default charset of a MySQL table, you can use the below syntax. The syntax is as follows −alter table yourTableName convert to character set yourCharsetName;Let us create a table and apply the above syntax to change the default charset. The query to create a table −mysql> create table CharsetDemo -> ( -> Id int, -> Name varchar(200), -> Age int -> ); Query OK, 0 rows affected (0.73 sec)Now you can change the charset of a table. The following is the query ...
Read MoreHow do I get the creation date of a MySQL table?
To get the creation date of MySQL table, use the information_schema. The syntax is as follows −SELECT create_time FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = 'yourDatabaseName’ AND table_name = 'yourTableName';Apply the above syntax for your database and the table name. Here I am using the database ‘business’ and table name is ‘student’. The query is as follows −mysql> SELECT create_time FROM INFORMATION_SCHEMA.TABLES -> WHERE table_schema = 'business' -> AND table_name = 'student';The following is the output displaying the creation time of a table −+---------------------+ | CREATE_TIME ...
Read MoreMySQL - CAST DECIMAL to INT?
Cast DECIMAL to INT with the help of FLOOR() function. The syntax is as follows −SELECT FLOOR(yourColumnName) from yourTableName where condition;Let us first create a table. The following is the query to create a table.mysql> create table DecimalToIntDemo -> ( -> Amount DECIMAL(3, 1) -> ); Query OK, 0 rows affected (0.88 sec)Now you can insert records into the table with the help of insert command. The query is as follows −mysql> insert into DecimalToIntDemo values(12.5); Query OK, 1 row affected (0.23 sec) mysql> insert into DecimalToIntDemo values(50.4); Query OK, 1 ...
Read MoreWhere does MySQL store database files?
To know where MySQL store database files, you can use the variable @@datadir. The query is as follows −mysql> select @@datadir;The following is the output that displays the path −+---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ 1 row in set (0.00 sec)Here is the snapshot where MySQL store database files i.e. the same path we got above −Now, let us verify whether ...
Read MoreSort by date & time in descending order in MySQL?
Let us create a table to sort date and time in ascending order. The query to create a table is as follows −mysql> create table SortByDateAndTime -> ( -> UserId int, -> UserName varchar(100), -> IssueDate date, -> IssueTime time -> ); Query OK, 0 rows affected (0.60 sec)Insert the records in the table using insert command. The query is as follows −mysql> insert into SortByDateAndTime values(1, 'John', '2018-12-16', '10:30'); Query OK, 1 row affected (0.14 sec) mysql> insert into SortByDateAndTime values(2, 'Bob', '2018-12-16', '10:10'); Query OK, 1 row affected (0.14 sec) ...
Read MoreShould I use COUNT(*) to get all the records in MySQL?
Whenever you want all the values like not null for a column then use count(*). This is faster than using count() method.The syntax to use count(*) is as follows −select count(*) as anyVariableName from yourTableName;To understand the above concept, let us first create a table. The query to create a table is as follows −mysql> create table CountingDemo -> ( -> BookId int -> ); Query OK, 0 rows affected (0.60 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into CountingDemo values(100); Query OK, 1 row affected (0.13 sec) ...
Read MoreHow can I simulate an array variable in MySQL?
Instead of simulating an array variable, use temporary table in MySQL. The syntax is as follows −create temporary table if not exists yourTemporaryTableName select yourColumnName1, yourColumnName2, ......N from yourTableName where conditionTo understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table SimulateArrayDemo -> ( -> Id int, -> FirstName varchar(100), -> LastName varchar(100 -> ) -> ); Query OK, 0 rows affected (1.25 sec)Insert some records in the table using ...
Read MoreDoes MySQL Boolean "tinyint(1)" holds values up to 127?
Let us learn some points about TINYINT type in MySQL −The TINYINT type takes 1 byte i.e. 8 bits.The TINYINT(N), where N indicates the display width you want.For example, TINYINT(1) can be used to display width which is 1.Let us learn about the minimum and maximum values −The maximum value for tinyint is= (2(8-1)-1) = 127 The minimum value for tinyint is = -(2(8-1)) = -128.The value will be between -128 to 127. This means TINYINT (1) does not affect the maximum and minimum value of tinyint.Let us check it −Firstly, create a table with a column set as TINYINT ...
Read MoreHow to ORDER BY RELEVANCE in MySQL?
To order by relevance, use the case statement. To understand the concept, let us create a table. The query to create a table is as follows −mysql> create table OrderByRelevance -> ( -> UserId int, -> UserName varchar(200) -> ); Query OK, 0 rows affected (0.51 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into OrderByRelevance values(101, 'Carol Smith'); Query OK, 1 row affected (0.18 sec) mysql> insert into OrderByRelevance values(102, 'Carol Adams'); Query OK, 1 row affected (0.17 sec) mysql> insert into ...
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