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MySQLi Articles
Page 283 of 341
How do you get the last access (and/or write) time of a MySQL database?
To get the last access time, try the following syntax −SELECT update_time FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = 'yourDatabaseName' AND table_name = 'yourTableName'The above syntax gives the last access information about MyISAM engine type.Here, our database is ‘business’ and we will be using the table with the name ‘twoprimarykeytabledemo'.To get last access time of MySQL database, use the following query.Case 1 − The query is as follows −mysql> SELECT update_time -> FROM INFORMATION_SCHEMA.TABLES -> WHERE table_schema = 'business' -> AND table_name = 'twoprimarykeytabledemo';The output is as follows −+---------------------+ | UPDATE_TIME ...
Read MoreHow to return static strings in MySQL?
In order to return static strings in MySQL, you can use UNION. Following is the syntax −select 'yourStringValue1' as yourAliasName UNION select 'yourStringValue2' as yourAliasName;Let us implement the above syntax to return static strings in MySQL. Following is the query −mysql> select 'HELLO' as staticStringsResult -> UNION -> select 'MySQL' as staticStringsResult;This will produce the following output −+---------------------+ | staticStringsResult | +---------------------+ | HELLO | | MySQL | +---------------------+ 2 rows in set (0.00 sec)In some MySQL versions, the above syntax does not work, therefore you ...
Read MoreHow to search for "ñ" and avoid records that include "n" in MySQL?
If you do not want all records that include “n” when you search for “ñ”, use the following syntax −select *from yourTableName where yourColumnName LIKE '%ñ%' COLLATE utf8_spanish_ci;Let us first create a table. Following is the query −mysql> create table NotIncludenDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ClientName varchar(20) -> ); Query OK, 0 rows affected (1.07 sec)Following is the query to insert some records in the table using insert command −mysql> insert into NotIncludenDemo(ClientName) values('John'); Query OK, 1 row affected (0.21 sec) mysql> insert into NotIncludenDemo(ClientName) values('Johñ'); Query OK, ...
Read MoreSet Blank spaces in column names with MySQL?
To set blank spaces in column names with MySQL, you can use the concept of backticks. Let us first create a table. Following is the query −mysql> create table blankSpacesDemo -> ( -> `Student Id` int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> `Student Full Name` varchar(100) -> ); Query OK, 0 rows affected (0.51 sec)Following is the query to insert some records in the table using insert command −mysql> insert into blankSpacesDemo(`Student Full Name`) values('John Smith'); Query OK, 1 row affected (0.16 sec) mysql> insert into blankSpacesDemo(`Student Full Name`) values('Carol Taylor'); Query OK, 1 row ...
Read MoreGet the average row length of a MySQL table
In order to get the average row length of a table in MySQL, you can use INFORMATION_SCHEMA.TABLES. Let us first create a table. Following is the query −mysql> create table Client_information -> ( -> Id int, -> Name varchar(10) -> ); Query OK, 0 rows affected (0.48 sec)Following is the query to insert some records in the table using insert command −mysql> insert into Client_information values(1, 'Larry'); Query OK, 1 row affected (0.14 sec) mysql> insert into Client_information values(2, 'Mike'); Query OK, 1 row affected (0.17 sec) mysql> insert into Client_information values(3, 'Sam'); Query ...
Read MoreHow to form a composite key to be unique in MySQL?
To form a composite key to be unique, you need to use ADD UNIQUE command. Following is the syntax −alter table yourTableName add unique yourUniqueName( yourColumnName1, yourColumnName2, .......N);Let us first create a table. Following is the query −mysql> create table makeCompositeKeyDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(40), -> StudentAge int, -> StudentGrade char(1) -> ); Query OK, 0 rows affected (2.34 sec)Now check the description of the table using DESC command. Following is the query −mysql> desc makeCompositeKeyDemo;This will produce the following output −+--------------+-------------+------+-----+---------+----------------+ | Field ...
Read MoreCan we use current_date() for table with column timestamp default in MySQL?
Use the CURRENT_TIMESTAMP instead of current_date() in MySQL for timestamp default current_date. Let us first create a table. Following is the query −mysql> create table defaultCurrent_DateDemo -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20), -> StudentAdmissionDate timestamp default CURRENT_TIMESTAMP -> ); Query OK, 0 rows affected (0.55 sec)Following is the query to insert some records in the table using insert command −mysql> insert into defaultCurrent_DateDemo(StudentName) values('Larry'); Query OK, 1 row affected (0.52 sec) mysql> insert into defaultCurrent_DateDemo(StudentName, StudentAdmissionDate) values('Chris', '2019-01-31'); Query OK, 1 row affected (0.18 sec)Following is the ...
Read MoreComparing two strings in MySQL?
To compare two strings, which are numbers, let us first create a table. Following is the query −mysql> create table compareTwoStringsDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Value varchar(100) -> ); Query OK, 0 rows affected (0.52 sec)Following is the query to insert some records in the table using insert command −mysql> insert into compareTwoStringsDemo(Value) values('1235667'); Query OK, 1 row affected (0.66 sec) mysql> insert into compareTwoStringsDemo(Value) values('999999'); Query OK, 1 row affected (0.11 sec) mysql> insert into compareTwoStringsDemo(Value) values('999888'); Query OK, 1 row affected (0.17 sec) mysql> ...
Read MoreHow to SELECT min and max value from the part of a table in MySQL?
To select min and max value from the part of a table in MySQL, use the following syntax −select min(yourColumnName) as yourAliasName1, max(yourColumnName) as yourAliasName2 from (select yourColumnName from yourTableName limit yourLimitValue) tbl1;Let us first create a table. Following is the query −mysql> create table MinAndMaxValueDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Value int -> ); Query OK, 0 rows affected (0.52 sec)Insert records in the table using insert command. Following is the query −mysql> insert into MinAndMaxValueDemo(Value) values(10); Query OK, 1 row affected (0.16 sec) mysql> insert into MinAndMaxValueDemo(Value) ...
Read MoreHow to display some columns (not all) in MySQL?
In order to show some columns, use NOT IN and set those columns which you do not want to display. Let us first create a table. Following is the query −mysql> create table student_Information -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(50), -> StudentAge int, -> StudentAddress varchar(100), -> StudentAllSubjectScore int -> ); Query OK, 0 rows affected (0.69 sec)Following is the query to display a description about the above table −mysql> desc student_Information;This will produce the following output −+------------------------+--------------+------+-----+---------+----------------+ | Field ...
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