I need to add a record if already a record with the primary key doesn't exist; otherwise existing record is to be updated. For this I am querying the db with the primary key. If no record exist, I am adding; otherwise updating. I am coding this in java using raw JDBC.
Is there a better way to do this?
insert … select … where not exist
INSERT INTO ... VALUES ... ON duplicate KEY UPDATE id = id
REPLACE INTO ... SELECT ... FROM ...
The most soft way to do this is to use special query INSERT ... ON DUPLICATE KEY UPDATE query in My Sql. It is much more effective than check is conflict exist on the application side.
Code snippet for example:
PreparedStatement statement = null;
try {
statement = connection.prepareStatement(
"INSERT INTO table (a,b,c) VALUES (?,?,?) ON DUPLICATE KEY UPDATE c=?;"
);
int paramIndex = 1;
statement.setInt(parameterIndex++, primaryKeyValue);
statement.setInt(parameterIndex++, secondValue);
statement.setInt(parameterIndex++, thirdValue);
statement.setInt(parameterIndex++, thirdValue);
int updatedCount = statement.executeUpdate();
} finally {
statement.close();
}
Another way would be REPLACE INTO which takes the same syntax as INSERT but removes the old entry when the primary key already exists before inserting.
The simplest and the most general way is to count the record before insert/update.
Pseudo Code:
SELECT COUNT(*) as recordCount FROM mytable WHERE keyField = ?
if (recordCount > 0) {
UPDATE mytable SET value1=? WHERE keyField = ?
} else {
INSERT INTO mytable (keyField, value1) VALUES (?, ?)
}
Related
Go easy on me, middle school teacher taking a CS class. I've got a Java program that asks for user name, height, weight, does some calculations and gives results to the user. I now need to store this data in a database. I can get the data to store until I start using primary and foreign keys.
Here is the error I can't figure out:
Error: java.sql.SQLIntegrityConstraintViolationException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'SQL180429151131780' defined on 'USERPROFILE'.
Here is my table:
drop table stayfitapp.userdata;
drop table stayfitapp.userprofile;
drop schema stayfitapp restrict;
create schema stayfitapp;
create table stayfitapp.userprofile
(
profileName varchar(255) not null primary key,
profileGender varchar(255) not null
);
create table stayfitapp.userdata
(
profileAge double not null,
profileWeight double not null,
profileHeight double not null,
profileWaistCircumference double not null,
profileHipCircumference double not null,
profileName varchar(255),
foreign key (profileName) references stayfitapp.userprofile(profileName)
);
Here is the section of the "app" that writes to the table...
public void save(){
try {
String query = "insert into stayfitapp.userprofile" + "(profileName, profileGender)" + "values" + "(?,?)";
String query2 = "insert into stayfitapp.userdata" + "(profileAge, profileWeight, profileHeight, profileWaistCircumference, profileHipCircumference)" + "values" + "(?,?,?,?,?)";
Connection myConnection = DriverManager.getConnection("jdbc:derby://localhost:1527/stayfitDB2", "username", "password");
Statement myStatement = myConnection.createStatement();
//Statement myStatement2 = myConnection.createStatement();
PreparedStatement prepared = myConnection.prepareStatement(query);
prepared.setString(1, profileName);
prepared.setString(2, profileGender);
PreparedStatement prepared2 = myConnection.prepareStatement(query2);
prepared2.setDouble(1, profileAge);
prepared2.setDouble(2, profileWeight);
prepared2.setDouble(3, profileHeight);
prepared2.setDouble(4, profileWaistCircumference);
prepared2.setDouble(5, profileHipCircumference);
int rowsAffected = prepared.executeUpdate();
int rowsAffected2 = prepared2.executeUpdate();
if(rowsAffected==0)
{
System.out.println("Warning: User data did not save!");
}
else
{
System.out.println("User info saved!");
}
}
catch(SQLException e)
{
System.out.println("Error: "+e.toString());
}
Your save() method will attempt to add the user to the stayfitapp.userprofile table. This table has a field called profileName. profileName is the "primary key" so no duplicate values are allowed.
The error that you are getting is saying that you cannot add(insert) the record to the table because the table already has a record with the same name.
Does your program work okay if you use a different name each time?
You will need to add some logic to your program to deal with the scenario where the profileName already exists in the table. This will probably involve deleting or updating the existing record.
This is the problem.
insert into stayfitapp.userprofile"
+ "(profileName, profileGender)" + "values" , etc
You have nothing to check to see if a record already exists. Something like this would work better.
insert into stayfitapp.userprofile
profileName, profileGender
select distinct ?, ?
from someSmallTable
where not exists (
select 1
from stayfitapp.userprofile
where profileName = ?
)
The someSmallTable bit depends on your database engine, which you didn't specify.
I ended up writing a method to check if the username was already in the profile table. If the username was a duplicate I only wrote to the data table. If the username was new I wrote to both tables.
Thank you for your help! I'm sure there was a more efficient method (figuratively and literally) but I'm on to my final project and nearly surviving an actual CS class.
I have a table with unique index to eliminate duplicates (simplified example)
CREATE TABLE `domain` (
`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`subdomain` VARCHAR(255) NOT NULL,
`domain` VARCHAR(63) NOT NULL,
`zone` VARCHAR(63) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE INDEX `UNIQUE` (`subdomain` ASC, `domain` ASC, `zone` ASC),
ENGINE = InnoDB;
I insert a lot of rows and i need to get primary keys returned (for other one-to-many inserts).
My problem is, that I insert a lot of duplicates and I need those keys returned too.
This is my solution which works, but isn't there more simple solution? With this I cannot use batch inserts and I want this to be most efficient.
PreparedStatement selectDomain = connection.prepareStatement("SELECT id FROM domain WHERE subdomain = ? AND domain = ? AND zone = ?");
PreparedStatement insertDomain = connection.prepareStatement("INSERT INTO domain(subdomain, domain, zone) VALUES (?,?,?)", Statement.RETURN_GENERATED_KEYS);
public int insertDomain(String subdomain, String domain, String zone) throws SQLException {
int domainId = 0;
selectDomain.setString(1, subdomain);
selectDomain.setString(2, domain);
selectDomain.setString(3, zone);
ResultSet resultSet = selectDomain.executeQuery();
if (resultSet.next()) {
domainId = resultSet.getInt(1);
} else {
insertDomain.setString(1, subdomain);
insertDomain.setString(2, subdomain);
insertDomain.setString(3, subdomain);
insertDomain.executeUpdate();
resultSet = insertDomain.getGeneratedKeys();
if (resultSet.next()) {
domainId = resultSet.getInt(1);
}
}
selectDomain.clearParameters();
insertDomain.clearParameters();
}
As I understand its not so easy approach for using batch execution. Your apporach is the best way to get the auto generated keys. There are few limitations of JDBC driver and it varies version to version, where getGeneratedKeys() works for single entry.
Please look into below links, it may help you :-
How to get generated keys from JDBC batch insert in Oracle?
http://docs.oracle.com/database/121/JJDBC/jdbcvers.htm#JJDBC28099
You could modify your INSERT to be something like this:
INSERT INTO domain (subdomain, domain, zone)
SELECT $subdomain, $domain, $zone
FROM domain
WHERE NOT EXISTS(
SELECT subdomain, domain, zone
FROM domain d
WHERE d.subdomain= $subdomain and d.domain=$domain and d.zone=$zone
)
LIMIT 1
Where $subdomain, $domain, $zone are the tag (properly quoted or as a placeholder of course) that you want to add if it isn't already there. This approach won't even trigger an INSERT (and the subsequent autoincrement wastage) if the tag is already there. You could probably come up with nicer SQL than that but the above should do the trick.
If your table is properly indexed then the extra SELECT for the existence check will be fast and the database is going to have to perform that check anyway.
Mysql tables
mysqltables
This is my query to insert data to the database.
public void voegSpelerToe(Speler speler, String spelNaam)
{
PreparedStatement invoerSpeler;
Speler huidigeSpeler = null;
try
{
Connection connection = PersistentieController.getInstance().getConnection();
invoerSpeler = connection.prepareStatement("INSERT INTO Speler " + "(naam, kleur, sector, aantalZilverstukken, Spel_naam) " + "VALUES ( ?, ?,?, ?, ?)");
invoerSpeler.setString(1, speler.getNaam());
invoerSpeler.setString(2, speler.getKleur());
invoerSpeler.setInt(3, speler.getSector().getCode());
invoerSpeler.setInt(4,speler.getKrediet());
invoerSpeler.setString(5, spelNaam);
invoerSpeler.executeUpdate();
} catch (SQLException sqlException)
{
sqlException.printStackTrace();
} finally
{
// PersistentieController.getInstance().closeConnection();
}
}
Everything has a value so I don't have nullexeptions.
But when I want to save the data I get this error:
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`projecteng62`.`speler`, CONSTRAINT `fk_Speler_Spel1` FOREIGN KEY (`Spel_naam`) REFERENCES `spel` (`naam`) ON DELETE CASCADE ON UPDATE CASCADE)
How can I insert data in the foreign key.
First It save data to the table Spel
and then i need to save data in the table speler but I get a problem wit the foreign Key.
Like table spel:
naam: Game12
aantalTeSPelenRondes: 2
table Speler:
naam : player1
kleur : green
sector : 2
aantalZilverStukken : 10
Spel_Naam: game12
Spel_naam must be the same as naam in table Spel
It is telling you that it is expecting the contents of Spel_Naam to exist in some row in spels naam attribute, but it does not exist.
To fully figure out the issue I would also need to see where you are inserting into spel.
But in the example input you provided
naam: Game12
Spel_Naam: game12
there is an issue because one is capitalized and the other is not. If this is actually how the data is set up, then that is likely your problem. But it seems you have the right idea, you need to insert into naam first, then into Spel_Naam.
In PostgreSQL user is a reserved keyword that is used in an internal table, however I also have a separate user table in my own database that I need to use. Whenever I try to execute INSERT or UPDATE statements on the table, it generates the following error: The column name 'id' was not found in this ResultSet.
This is the Java code I am currently using:
PreparedStatement stat1 = conn.prepareStatement("SELECT id FROM user;");
PreparedStatement stat2 = conn.prepareStatement("UPDATE user SET date_created = ? , last_updated = ? , uuid = ? WHERE id = ?;");
ResultSet rs = stat1.executeQuery();
while(rs.next()){
UUID uuid = UUID.randomUUID();
String tempId = uuid.toString();
stat2.setTimestamp(1, curDate);
stat2.setTimestamp(2, curDate);
stat2.setString(3, tempId);
stat2.setLong(4,rs.getLong("id"));
stat2.executeUpdate();
}
So my question is, how could I insert or update the values in my personal user table without interfering with the keyword restriction?
Use this:
prepareStatement("UPDATE \"user\" set date_created = ?")
Or, better yet, rename your user table to something else, like users:
ALTER TABLE "user" RENAME TO users;
Escape the table name like this
select * from "user";
I'm using iBatis/Java and Postgres 8.3.
When I do an insert in ibatis i need the id returned.
I use the following table for describing my question:
CREATE TABLE sometable ( id serial NOT NULL, somefield VARCHAR(10) );
The Sequence sometable_id_seq gets autogenerated by running the create statement.
At the moment i use the following sql map:
<insert id="insertValue" parameterClass="string" >
INSERT INTO sometable ( somefield ) VALUES ( #value# );
<selectKey keyProperty="id" resultClass="int">
SELECT last_value AS id FROM sometable_id_seq
</selectKey>
</insert>
It seems this is the ibatis way of retrieving the newly inserted id. Ibatis first runs a INSERT statement and afterwards it asks the sequence for the last id.
I have doubts that this will work with many concurrent inserts.
Could this cause problems? Like returning the id of the wrong insert?
( See also my related question about how to get ibatis to use the INSERT .. RETURING .. statements )
This is definitely wrong. Use:
select currval('sometable_id_seq')
or better yet:
INSERT INTO sometable ( somefield ) VALUES ( #value# ) returning id
which will return you inserted id.
Here is simple example:
<statement id="addObject"
parameterClass="test.Object"
resultClass="int">
INSERT INTO objects(expression, meta, title,
usersid)
VALUES (#expression#, #meta#, #title#, #usersId#)
RETURNING id
</statement>
And in Java code:
Integer id = (Integer) executor.queryForObject("addObject", object);
object.setId(id);
I have another thought. ibatis invokes the insert method delegate the Class: com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate,with the code:
try {
trans = autoStartTransaction(sessionScope, autoStart, trans);
SelectKeyStatement selectKeyStatement = null;
if (ms instanceof InsertStatement) {
selectKeyStatement = ((InsertStatement) ms).getSelectKeyStatement();
}
// Here we get the old value for the key property. We'll want it later if for some reason the
// insert fails.
Object oldKeyValue = null;
String keyProperty = null;
boolean resetKeyValueOnFailure = false;
if (selectKeyStatement != null && !selectKeyStatement.isRunAfterSQL()) {
keyProperty = selectKeyStatement.getKeyProperty();
oldKeyValue = PROBE.getObject(param, keyProperty);
generatedKey = executeSelectKey(sessionScope, trans, ms, param);
resetKeyValueOnFailure = true;
}
StatementScope statementScope = beginStatementScope(sessionScope, ms);
try {
ms.executeUpdate(statementScope, trans, param);
}catch (SQLException e){
// uh-oh, the insert failed, so if we set the reset flag earlier, we'll put the old value
// back...
if(resetKeyValueOnFailure) PROBE.setObject(param, keyProperty, oldKeyValue);
// ...and still throw the exception.
throw e;
} finally {
endStatementScope(statementScope);
}
if (selectKeyStatement != null && selectKeyStatement.isRunAfterSQL()) {
generatedKey = executeSelectKey(sessionScope, trans, ms, param);
}
autoCommitTransaction(sessionScope, autoStart);
} finally {
autoEndTransaction(sessionScope, autoStart);
}
You can see that the insert and select operator are in a Transaction. So I think there is no concureency problem with the insert method.