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Database Articles
Page 302 of 547
MySQL query to find duplicate tuples and display the count?
To find duplicate tuples, use GROUP BY HAVING clause. Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.80 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Chris'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values(101, 'David'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(101, 'Mike'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(100, 'Carol'); Query OK, 1 row affected (0.17 sec) ...
Read MoreAdding a new NOT NULL column to an existing table with records
To add a new NOT NULL column to an already created table, use ALTER command. 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 (0.60 sec)Following is the query to add a new NOT NULL column to an existing table −mysql> alter table DemoTable add column StudentAge int NOT NULL; Query OK, 0 rows affected (0.52 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command −mysql> insert into DemoTable(StudentName, ...
Read MoreSort character values from a column mixed with character and numbers in MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Code varchar(20) -> ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('J23'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable values('C13'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('A61'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('D56'); 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 ...
Read MoreHow to fetch only a single result from a table in Java-MySQL?
Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (1.37 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(101, 'Chris'); Query OK, 1 row affected (0.54 sec) mysql> insert into DemoTable values(102, 'David'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(103, 'Mike'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select statement −mysql> select * from DemoTable;This will produce the following output −+------+-------+ | Id ...
Read MoreHow to insert only a single column into a MySQL table with Java?
Use INSERT INTO statement in the Java-MySQL connection code to insert a column.Let us first create a table −mysql> create table DemoTable -> ( -> Name varchar(20) -> ); Query OK, 0 rows affected (0.54 sec)Here is the Java code to insert only a single column into a MySQL table.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; public class InsertOneColumnDemo { public static void main(String[] args) { Connection con = null; PreparedStatement ps = null; try { con = DriverManager.getConnection("jdbc:mysql://localhost:3306/web?" + "useSSL=false", "root", "123456"); ...
Read MoreHow to treat MySQL longtext as integer in MySQL query?
Let us first create a table −mysql> create table DemoTable -> ( -> Value longtext -> ); Query OK, 0 rows affected (0.94 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('778437437447488487476464644433334'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('9998888485775775757577578585'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('8888874757757757757757575675656'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('988757757574646'); Query OK, 1 row affected (0.09 sec)Display all records from the table using select statement −mysql> select * from DemoTable;This will produce the following ...
Read MoreWhat would happen if we run SELECT WHERE columnName = zero in MySQL?
The following syntax will fetch all the values from the column −select * from yourTableName where yourColumnName=0;Let us first create a table −mysql> create table DemoTable1791 ( FirstName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1791 values('David'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1791 values('John'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1791 values('Carol'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1791;This ...
Read MoreMySQL query to fetch records from a range of months?
Let us first create a table −mysql> create table DemoTable1795 ( Name varchar(20), DueDate date ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1795 values('John', '2018-07-21'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1795 values('Sam', '2019-10-21'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1795 values('Sam', '2019-01-10'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1795 values('Mike', '2018-12-31'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> ...
Read MoreHow to auto increment with 1 after deleting data from a MySQL table?
For this, you can use TRUNCATE TABLE command. Let us first create a table −mysql> create table DemoTable1796 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1796(StudentName) values('Chris Brown'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1796(StudentName) values('David Miller'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1796(StudentName) values('John Doe'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statementmysql> select ...
Read MoreUNIX_TIMESTAMP with date in MySQL query to fetch records after a specific date in different format?
For this, you can use STR_TO_DATE(), since we have date records in the following format: 21/11/2019.Let us first create a table −mysql> create table DemoTable1808 ( AdmissionDate varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1808 values('21/11/2019'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1808 values('01/01/2018'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1808 values('26/09/2017'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1808;This will ...
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