Vertica Prepared Statement Return Generated Keys
- Vertica Prepared Statement Return Generated Keys Pdf
- Vertica Prepared Statement Return Generated Keys 2016
- Vertica Prepared Statement Return Generated Keys Pdf
- Vertica Prepared Statement Return Generated Keys In Windows 10
- JDBC Tutorial
- JDBC Examples
- JDBC Useful Resources
- Selected Reading
In this example, while creating an instance of PreparedStatement, we have passed 2 arguments. 1st is the query itself and 2 nd is “Statement.RETURNGENERATEDKEYS“, which will help us to get the primary key value of the new row. The below code. Feb 26, 2020 With version 9.2, Vertica has removed support for pre-join and range segmentation projections. If a table's only superprojection is one of these projection types, the projection is regarded as unsafe. Before upgrading to 9.2 or higher, you are strongly urged to check your database for unsupported projections. The driver will ignore the flag if the SQL statement is not an INSERT statement, or an SQL statement able to return auto-generated keys (the list of such statements is vendor-specific). This method should be used when the returned row count may exceed Integer.MAXVALUE.
Once a connection is obtained we can interact with the database. The JDBC Statement, CallableStatement, and PreparedStatement interfaces define the methods and properties that enable you to send SQL or PL/SQL commands and receive data from your database.
They also define methods that help bridge data type differences between Java and SQL data types used in a database.
Ssh public and private key generation. The following table provides a summary of each interface's purpose to decide on the interface to use.
| Interfaces | Recommended Use |
|---|---|
| Statement | Use this for general-purpose access to your database. Useful when you are using static SQL statements at runtime. The Statement interface cannot accept parameters. |
| PreparedStatement | Use this when you plan to use the SQL statements many times. The PreparedStatement interface accepts input parameters at runtime. |
| CallableStatement | Use this when you want to access the database stored procedures. The CallableStatement interface can also accept runtime input parameters. |
The Statement Objects
Creating Statement Object
Before you can use a Statement object to execute a SQL statement, you need to create one using the Connection object's createStatement( ) method, as in the following example −
Once you've created a Statement object, you can then use it to execute an SQL statement with one of its three execute methods.
boolean execute (String SQL): Returns a boolean value of true if a ResultSet object can be retrieved; otherwise, it returns false. Use this method to execute SQL DDL statements or when you need to use truly dynamic SQL.
int executeUpdate (String SQL): Returns the number of rows affected by the execution of the SQL statement. Use this method to execute SQL statements for which you expect to get a number of rows affected - for example, an INSERT, UPDATE, or DELETE statement.
ResultSet executeQuery (String SQL): Returns a ResultSet object. Use this method when you expect to get a result set, as you would with a SELECT statement.
Closing Statement Object
Just as you close a Connection object to save database resources, for the same reason you should also close the Statement object.
A simple call to the close() method will do the job. If you close the Connection object first, it will close the Statement object as well. However, you should always explicitly close the Statement object to ensure proper cleanup.
For a better understanding, we suggest you to study the Statement - Example tutorial.
The PreparedStatement Objects
The PreparedStatement interface extends the Statement interface, which gives you added functionality with a couple of advantages over a generic Statement object.
This statement gives you the flexibility of supplying arguments dynamically.
Creating PreparedStatement Object
All parameters in JDBC are represented by the ? symbol, which is known as the parameter marker. You must supply values for every parameter before executing the SQL statement.
The setXXX() methods bind values to the parameters, where XXX represents the Java data type of the value you wish to bind to the input parameter. If you forget to supply the values, you will receive an SQLException.
Each parameter marker is referred by its ordinal position. The first marker represents position 1, the next position 2, and so forth. This method differs from that of Java array indices, which starts at 0.
All of the Statement object's methods for interacting with the database (a) execute(), (b) executeQuery(), and (c) executeUpdate() also work with the PreparedStatement object. However, the methods are modified to use SQL statements that can input the parameters.
Closing PreparedStatement Object
Just as you close a Statement object, for the same reason you should also close the PreparedStatement object.
A simple call to the close() method will do the job. If you close the Connection object first, it will close the PreparedStatement object as well. However, you should always explicitly close the PreparedStatement object to ensure proper cleanup.
For a better understanding, let us study Prepare - Example Code.
The CallableStatement Objects
Just as a Connection object creates the Statement and PreparedStatement objects, it also creates the CallableStatement object, which would be used to execute a call to a database stored procedure.
Creating CallableStatement Object
Suppose, you need to execute the following Oracle stored procedure −
NOTE: Above stored procedure has been written for Oracle, but we are working with MySQL database so, let us write same stored procedure for MySQL as follows to create it in EMP database −
Three types of parameters exist: IN, OUT, and INOUT. The PreparedStatement object only uses the IN parameter. The CallableStatement object can use all the three.
Here are the definitions of each −
| Parameter | Description |
|---|---|
| IN | A parameter whose value is unknown when the SQL statement is created. You bind values to IN parameters with the setXXX() methods. |
| OUT | A parameter whose value is supplied by the SQL statement it returns. You retrieve values from theOUT parameters with the getXXX() methods. |
| INOUT | A parameter that provides both input and output values. You bind variables with the setXXX() methods and retrieve values with the getXXX() methods. |
The following code snippet shows how to employ the Connection.prepareCall() method to instantiate a CallableStatement object based on the preceding stored procedure −
The String variable SQL, represents the stored procedure, with parameter placeholders.
Using the CallableStatement objects is much like using the PreparedStatement objects. You must bind values to all the parameters before executing the statement, or you will receive an SQLException.
If you have IN parameters, just follow the same rules and techniques that apply to a PreparedStatement object; use the setXXX() method that corresponds to the Java data type you are binding.
When you use OUT and INOUT parameters you must employ an additional CallableStatement method, registerOutParameter(). The registerOutParameter() method binds the JDBC data type, to the data type that the stored procedure is expected to return.
Once you call your stored procedure, you retrieve the value from the OUT parameter with the appropriate getXXX() method. This method casts the retrieved value of SQL type to a Java data type.
Closing CallableStatement Object
Just as you close other Statement object, for the same reason you should also close the CallableStatement object.
A simple call to the close() method will do the job. If you close the Connection object first, it will close the CallableStatement object as well. However, you should always explicitly close the CallableStatement object to ensure proper cleanup.
For a better understanding, I would suggest to study Callable - Example Code.
Vertica Prepared Statement Return Generated Keys Pdf
- Related Questions & Answers
- Selected Reading
Vertica Prepared Statement Return Generated Keys 2016
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.
In MySQL database you can declare a column auto increment using the following syntax.
While inserting records in a table there is no need to insert value under the auto-incremented column. These will be generated automatically.
Vertica Prepared Statement Return Generated Keys Pdf
For example, in a table if we have a column with name ID and data type INT, which is auto-incremented and, if we already have 6 records in that table. When you insert the next record using the INSERT statement the ID value of the new record will be 7 and the ID value of its next record will be 8.
(You can specify the initial value and interval for these auto-incremented columns).
Retrieving the auto-incremented values
If you insert records into a table which contains auto-incremented column, using a PreparedStatement object.
You can retrieve the values of that particular column, generated by the current PreparedStatement object using the getGeneratedKeys() method.
Example
Let us create a table with name sales in MySQL database, with one of the columns as auto-incremented, using CREATE statement as shown below −
Vertica Prepared Statement Return Generated Keys In Windows 10
Now, to insert records into this table using PreparedStatement object and, to retrieve the auto-incremented values generated by it −
- Register the Driver class of the desired database using the registerDriver() method of the DriverManager class or, the forName() method of the class named Class.
- Create a Connection object by passing the URL of the database, user-name and password of a user in the database (in string format) as parameters to the getConnection() method of the DriverManager class.
- Create a PreparedStatement object using the prepareStatement() method of the connection interface.
To this method pass the INSERT statement with bind variables in string format as one parameter and, Statement.RETURN_GENERATED_KEYS as other parameter as −
- Set values of each record to the bind variables using the setXXX() methods and, add it to batch.
After adding values of all the records to the batch, execute the batch using the executeBatch() method.
- Finally, get the auto-incremented keys generated by this PreparedStatement object using the getGeneratedKeys() method.
Following JDBC program inserts 5 records into the Sales table (created above) using PreparedStatement, retrieves and displays the auto-incremented values generated by it.