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MySQL Articles
Page 345 of 355
MySQL pagination without double-querying?
To work with MySQL pagination, firstly let us see how to use CREATE command and use it to create a table. mysql>CREATE table RowCountDemo -> ( -> ID int, -> Name varchar(100) -> ); Query OK, 0 rows affected (0.95 sec) Records are inserted with the help of INSERT command. mysql>INSERT into RowCountDemo values(1, 'Larry'); Query OK, 1 row affected (0.15 sec) mysql>INSERT into RowCountDemo values(2, 'John'); Query OK, 1 row affected (0.13 sec) mysql>INSERT into RowCountDemo values(3, 'Bela'); Query OK, 1 row ...
Read MoreSorting varchar field numerically in MySQL?
‘LPAD(lower(column_name))’ is used to sort the varchar field numerically in MySQL. Let us see an example. Firstly, we will create a table. The CREATE command is used to create a table. mysql> create table SortingvarcharDemo -> ( -> List varchar(10) -> ); Query OK, 0 rows affected (0.82 sec) Records are inserted with the help of INSERT command. mysql> insert into SortingvarcharDemo values("99"); Query OK, 1 row affected (0.12 sec) mysql> insert into SortingvarcharDemo values("9"); Query OK, 1 row affected (0.17 sec) mysql> insert into SortingvarcharDemo ...
Read MoreUsage of backtick in SQL statements?
The backtick can be used in MySQL. To create a table, we can put table_name in backticks. Example of Backtick in MySQL. The CREATE command is used to create a table. Here, we have added the table name using the backtick symbol. mysql> create table `backtickSymbol` -> ( -> uniId int -> ); Query OK, 0 rows affected (1.65 sec) Records are inserted with the help of INSERT command. mysql> insert into `backtickSymbol` values(1); Query OK, 1 row affected (0.20 sec) mysql> insert into `backtickSymbol` values(2); Query ...
Read MoreGenerating a unique random 10 character string using MySQL?
In order to generate a 10 character string, we can use inbuilt functions ‘rand()’ and ‘char()’. The following is the query to generate random 10 character string. mysql> SELECT concat( - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97), - > char(round(rand()*25)+97) - > )AS Random10CharacterString; ...
Read MoreMySQL ON vs USING?
In general, we use ON in MySQL. In Joins, we use ON in a set of columns. USING is useful when both the tables share a column of the exact same name on which they join. Example of On. Creating our first table. mysql> CREATE table ForeignTableDemo -> ( -> Id int, -> Name varchar(100), - > FK int - > ); Query OK, 0 rows affected (0.47 sec) Creating our second table. mysql> CREATE table PrimaryTableDemo - > ...
Read MoreHow to use a function for default value in MySQL?
We cannot use a function for default value in MySQL, but we can use triggers. Let us see an example. First, we will create a table. The CREATE command is used to create a table. mysql> CREATE table TbLFunctionTrigger - > ( - > id int, - > username varchar(100) - > ); Query OK, 0 rows affected (0.55 sec) The following is the syntax to create a trigger and include a default value. CREATE TRIGGER anyName BEFORE INSERT ON yourTableName FOR EACH ROW ...
Read MoreHow to use MySQL JOIN without ON condition?
We can use ‘cross join’ without on condition. Cross join gives the result in cartesian product form. For instance, if in one table there are 3 records and another table has 2 records, then the first record will match with all the second table records. Then, the same process will be repeated for second record and so on. Example of cross join Creating the first table mysql> CREATE table ForeignTableDemo - > ( - > Id int, - > Name varchar(100), - > FK int ...
Read MoreDifference between two timestamps in seconds in MySQL?
Let us now see the following methods to calculate the time difference between two timestamps in seconds. Method The following is the query to calculate the difference between two timestamps. mysql> SELECT TIMESTAMPDIFF(SECOND, '2018-10-17 11:51:55', '2018-10-17 11:51:58'); The following is the output in seconds. +---------------------------------------------------------------------+ | TIMESTAMPDIFF(SECOND, '2018-10-17 11:51:55', '2018-10-17 11:51:58') | +---------------------------------------------------------------------+ | ...
Read MoreHow to do a batch insert in MySQL?
To do a batch insert, we need to use all column names with parenthesis, separated by ‘, ’. Let us see an example. First, we will create a table. The following is the CREATE command to create a table. mysql> CREATE table MultipleRecordWithValues - > ( - > id int, - > name varchar(100) - > ); Query OK, 0 rows affected (0.88 sec) The following is the syntax of batch insert. INSERT into yourTableName values(column1, column2, ....N), (column1, column2, ....N), (column1, column2, ....N), ...........N; ...
Read MoreWhen should I use a composite index in MySQL?
The composite index can be used when we are using sub queries. The advantages of using composite index are in case of. Joining Filtering Selecting The following is the syntax of index. index(column_name1, column_name2, column_name3, column_name4, ............................N) Let us create a table first and within that we have set index. mysql> create table MultipleIndexDemo - > ( - > id int, - > FirstName varchar(100), - > LastName varchar(100), - > Address varchar(200), - > index(id, LastName, ...
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