java.sql.SQLException: Duplicate entry for key when trying to insert in database from java

Question

this is my table in mysql

CREATE TABLE `mydb`.`mytab` (

    `email` VARCHAR(45) NOT NULL,
    `name` VARCHAR(45) NULL,

    PRIMARY KEY (`email`));

and my code in java is

Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/spacespacer", "root", "");
PreparedStatement state=con.prepareStatement("INSERT INTO `spacespacer`.`mytab` VALUES (?, ?);");
state.setString(1, "email");
state.setString(2, "name");
state.executeUpdate();

and this is what i get when i run the file in netbeans

run:
Exception in thread "main" java.sql.SQLException: Duplicate entry 'email' for key 'PRIMARY'
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2847)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1531)
at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1347)
at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:958)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1957)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1880)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1741)
at spacespacer.SpaceSpacer.main(SpaceSpacer.java:30)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

so how do i get it to work?

thanks for replying

Check the value that you are trying to insert and then check if it is already on the table. The error states that you are trying to insert the same value in a primary key field which only allows the value just once. — Jorge Campos
– Jorge Campos, Commented Jun 11, 2014 at 16:44
i solved this just by deleting the table from my local db, and then run, so hibernate will create the tables from the start, now its work fine. — Ashrik Ahamed
– Ashrik Ahamed, Commented Mar 22, 2023 at 10:17

Rakesh KR · Accepted Answer · 2014-06-11 16:55:44Z

2

In your table you have already have an entry with "email".

Here in the table column email is set as PrimaryKey. So duplication cannot be possible.

Note :

Your Table is mytab under database mydb. But you are inserting into spacespacer.mytab.

edited Jun 11, 2014 at 16:55

answered Jun 11, 2014 at 16:43

Rakesh KR

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1 Comment

AminePaleo Over a year ago

oh ok, i already had a value named "email" in, thanks for the answer!

Vivin · Accepted Answer · 2014-06-11 16:50:45Z

0

This is because you already have "email" in your table which you have set as primary key. So you cannot add more emails called "email". Try querying your table to check if you already have that record. As a suggestion, don't use email as a primary key. It will result in slow indexing and searching since its a varchar and can be long.

answered Jun 11, 2014 at 16:50

Vivin

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Comments

Paul · Accepted Answer · 2014-06-11 17:02:52Z

0

Do not use 'email' as key, even when it is unique. Rule of thumb, use int or long as primary key.

answered Jun 11, 2014 at 17:02

Paul

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2 Comments

AminePaleo Over a year ago

i could not retrieve the generated key in java when i use statement.getGeneratedKeys() it only shows the number of rows inserted in java, not the actual number of keys

vanOekel Over a year ago

@AminePaleo Use ps = connection.prepareStatement(query, Statement.RETURN_GENERATED_KEYS) and after ps.executeUpdate() you can get the generated keys in a resultset via ps.getGeneratedKeys().

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