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Articles on Trending Technologies
Technical articles with clear explanations and examples
Find "greatest" between two columns and display with some records already null in MySql
Let us first create a table −mysql> create table DemoTable -> ( -> Value1 int, -> Value2 int -> ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(78, 89); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values(19, null); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(null, 0); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values(null, 95); Query OK, 1 row affected (0.15 sec)Display all records from the table using select statement −mysql> ...
Read MoreOrder records and delete n rows in MySQL
Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20) -> ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(FirstName) values('Chris'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(FirstName) values('Adam'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(FirstName) values('John'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(FirstName) values('David'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(FirstName) values('Mike'); Query OK, 1 ...
Read MoreAdd a single day to datetime field with MySQL INTERVAL
Let us first create a table −mysql> create table DemoTable -> ( -> DueDate date ->); Query OK, 0 rows affected (2.11 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-01-21'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('2018-12-31'); Query OK, 1 row affected (0.47 sec) mysql> insert into DemoTable values('2018-12-30'); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable values('2017-02-26'); Query OK, 1 row affected (0.47 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+------------+ ...
Read MoreShifting values of rows in MySQL to change the existing id values for existing rows?
Let us first create a table −mysql> create table DemoTable -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20) -> ); Query OK, 0 rows affected (1.07 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentName) values('Chris'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable(StudentName) values('Robert'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(StudentName) values('David'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(StudentName) values('Mike'); Query OK, 1 row affected (0.10 sec)Display all records from the table using select statement ...
Read MoreMySQL query to delete last two words from every column value
For this, you can use the LEFT() function from MySQL. Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(10) -> ); Query OK, 0 rows affected (0.71 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.07 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.11 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+--------+ | ...
Read MoreCan we use the word user for a MySQL table?
You cannot use “user” for a MySQL table because it is a reserved word in MySQL. You can change the name from user to users or something else or you can use backticks around the user word.The word user can be used to create a user or can select a user list from the MySQL database.Let us first create a table. Here, we have used the table name users −mysql> create table users -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserName varchar(20), -> UserAge int -> ); Query OK, 0 rows ...
Read MoreMySQL Select where timestamp is in the current hour?
For this, you can use CURTIME(). Let us first create a table −mysql> create table DemoTable -> ( -> ArrivalTime timestamp -> ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-10-26 17:55:55'); Query OK, 1 row affected (0.46 sec) mysql> insert into DemoTable values('2019-10-26 18:00:00'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('2019-10-26 18:55:00'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('2018-10-26 16:00:10'); Query OK, 1 row affected (0.20 sec)Display all records from the table using select ...
Read MoreHow to declare a variable inside a procedure in MySQL?
You can use the DECLARE command to declare a variable inside a MySQL procedure. Let us create a stored procedure in MySQL −mysql> DELIMITER // mysql> CREATE PROCEDURE DECLARE_VARIABLE_DEMO(IN value int) -> BEGIN -> DECLARE searchValue int; -> set searchValue=value; -> if searchValue=10 then -> select searchValue+100; -> else -> select searchValue; -> end if; -> END -> // Query OK, 0 rows affected (0.17 sec) mysql> DELIMITER ;Above, we have declared a variable. Now, let us call the stored procedure using CALL command −mysql> call DECLARE_VARIABLE_DEMO(10);This will ...
Read MoreWhere we should close a connection in JDBC and MySQL?
You need to close connection in finally block. Following is the Java code to close connection in JDBC and MySQL −import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.SQLException; public class CloseConnectionDemoInFinallyBlock { public static void main(String[] args) { String JDBCURL = "jdbc:mysql://localhost:3306/web?useSSL=false"; Connection con = null; try { con = DriverManager.getConnection(JDBCURL, "root", "123456"); System.out.println("connection is open"); } catch (Exception e) { e.printStackTrace(); } finally { try { con.close(); } catch (SQLException sqlException) { sqlException.printStackTrace(); } } } }This will produce the following output −connection is openHere is the screenshot of the output −
Read MoreFiltering data in a table for a required condition to eliminate a specific record with MySQL
For this, you can use NOT LIKE operator. Let us first create a table −mysql> create table DemoTable -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20), -> StudentAdmissionYear varchar(20) -> ); Query OK, 0 rows affected (1.22 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentName, StudentAdmissionYear) values('Chris', '2017'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(StudentName, StudentAdmissionYear) values('David', '2015'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(StudentName, StudentAdmissionYear) values('Bob', '2019'); Query OK, 1 row affected (0.18 sec) mysql> insert ...
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