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MySQL Articles
Page 336 of 355
Set MySQL DECIMAL with accuracy of 10 digits after the comma?
As you know the DECIMAL() method takes two parameter. The first parameter tells about the total number of digits and second parameter tells about number of digits after decimal point. Therefore, if you use DECIMAL(10, 10) that means you can use only 10 fractional digit.For Example: Store 0.9999999999 with DECIMAL(20, 10).To understand what we discussed above, let us create a table. The query to create a table is as follows:mysql> create table Decimal_Demo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Price DECIMAL(20, 10), -> PRIMARY KEY(Id) ...
Read MoreImprove MySQL Search Performance with wildcards (%%)?
No, MySQL won’t improve search performance whenever you have leading wildcards because MySQL will be unable to use the index. If you change to ‘anyLetter%’ then it will be able to use indexThe below syntax is better to use with trailing wildcards. The syntax is as follows −SELECT *FROM yourTableName WHERE yoorColumnName LIKE ‘anyLetter%’;The query to create a table is as follows −mysql> create table TrailingWildCardDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name Varchar(20), -> PRIMARY KEY(Id) -> ); Query OK, 0 ...
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 ...
Read MoreReturn order of MySQL SHOW COLUMNS?
To return order of MySQL SHOW COLUMNS, you need to use ORDER BY clause. The syntax is as follows −SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE table_name = ‘yourTableName’ AND column_name LIKE 'yourStartColumnName%' ORDER BY column_name DESC;Let us create a table in database TEST. The query to create a table is as follows −mysql> create table OrderByColumnName -> ( -> StudentId int, -> StudentFirstName varchar(10), -> StudentLastName varchar(10), -> StudentAddress varchar(20), -> StudentAge int, -> StudentMarks int ...
Read MoreHow to select all records that are 10 minutes within current timestamp in MySQL?
You can select all records that are 10 minutes within current timestamp using the following syntax−SELECT *FROM yourTableName WHERE yourColumnName > = DATE_SUB(NOW(), INTERVAL 10 MINUTE);To understand the above syntax, let us create a table. The query to create a table is as follows−mysql> create table users -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserName varchar(20), -> UserLastseen datetime, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.91 sec)Insert some records in the table using insert command. The query is as follows−mysql> insert into users(UserName, UserLastseen) values('Larry', '2019-01-15 02−45−00'); Query ...
Read MoreShould I store a field PRICE as an int or as a float in the database?
You do not need to store a field PRICE as an int or as float in the database. For this, you can set the DECIMAL()..Most of the time integers can be used to represent the float point numbers and these integers are internally cast into DECIMAL() data type. Therefore, if you have field PRICE then always use DECIMAL() data type. The syntax is as follows −DECIMAL(M, D);Here, M represents the ‘TotalNumberOfDigit’ and D represents the ‘Number OfDigitAfterDecimalPoint’.To understand the above concept, let us create a table with field PRICE as DECIMAL data type. The query is as follows −mysql> create ...
Read MoreMYSQL: Can you pull results that match like 3 out of 4 expressions?
You can use CASE statement to get the results that match some expressions−SELECT *FROM yourTableName WHERE CASE WHEN yourColumnName1 = yourValue1 THEN 1 ELSE 0 END + CASE WHEN yourColumnName2 = yourValue2 THEN 1 ELSE 0 END + CASE WHEN yourColumnName3 = yourValue3 THEN 1 ELSE 0 END + . . CASE WHEN yourColumnNameN = yourValueN THEN 1 ELSE 0 END > = 3;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table UserInformation -> ( -> Id int NOT NULL AUTO_INCREMENT, ...
Read MoreUsing LIKE for two where clauses in MySQL?
You don’t need to use two where clauses. Use two conditions using the LIKE operator and AND operator.To understand how to use LIKE for this, let us create a table. The query to create a table is as follows −mysql> create table WhereDemo -> ( -> Id int, -> Name varchar(20) -> ); 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 WhereDemo values(101, 'Maxwell'); Query OK, 1 row affected (0.14 sec) mysql> insert into WhereDemo values(110, 'David'); Query ...
Read MoreHow to change collation to utf8_bin in a single line?
You need to use ALTER command to change collation to utf8_bin. The syntax is as follows:ALTER TABLE yourTableName COLLATE utf8_general_ci;To understand the above syntax, let us create a table. The query to create a table is as follows:mysql> create table CollateDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(20), -> Age int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.98 sec)Check the DDL of the table. The syntax is as follows:SHOW CREATE TABLE yourTableName;Let us now check the DDL of our table:mysql> show create table CollateDemo;The following is ...
Read MoreFind a list of invalid email address from a table in MySQL?
To find invalid email address, use the below syntax −SELECT yourColumnName FROM yourTableName WHERE yourColumnName NOT LIKE '%_@_%._%';The above syntax will give the list of all invalid email addresses. To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table FindInvalidEmailAddressDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(20), -> EmailAddress varchar(40), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.75 sec)Now you can insert some records in the table using insert command. We have inserted some invalid ...
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