You can lock a record, set of records, database table, table-space etc. and when we do we cannot change the locked values. Following are the types of locking in JDBC:Row and Key Locks: These are used to lock a particular row. Using these locks, you can achieve concurrency.Page Locks: These are used to lock a page. If you apply this, whenever the contents of a row changes, the database locks the entire page which holds the row. If you need to update/change large number of rows at once you can use this lock.Table Locks: You can lock a table using ... Read More

The ResultSetMetaData provides information about the obtained ResultSet object like, the number of columns, names of the columns, datatypes of the columns, name of the table etc…Following are some methods of ResultSetMetaData class.MethodDescriptiongetColumnCount()Retrieves the number of columns in the current ResultSet object.getColumnLabel()Retrieves the suggested name of the column for use.getColumnName()Retrieves the name of the column.getTableName()Retrieves the name of the table.Exampleimport java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.Statement; public class ResultSetMetadataExample {    public static void main(String args[]) throws Exception {       //Registering the Driver       DriverManager.registerDriver(new com.mysql.jdbc.Driver());       //Getting the connection   ... Read More

Generally, Data about data is known as metadata. The DatabaseMetaData interface provides methods to get information about the database you have connected with like, database name, database driver version, maximum column length etc...Following are some methods of DatabaseMetaData class.MethodDescriptiongetDriverName()Retrieves the name of the current JDBC drivergetDriverVersion()Retrieves the version of the current JDBC drivergetUserName()Retrieves the user name.getDatabaseProductName()Retrieves the name of the current database.getDatabaseProductVersion()Retrieves the version of the current database.getNumericFunctions()Retrieves the list of the numeric functions available with this database.getStringFunctions()Retrieves the list of the numeric functions available with this database.getSystemFunctions()Retrieves the list of the system functions available with this database.getTimeDateFunctions()Retrieves the list ... Read More

A ResultSet interface in JDBC represents the tabular data generated by SQL queries. It has a cursor which points to the current row. Initially this cursor is positioned before first row.You can move the cursor using the next() method and, you can retrieve the column values of a row using the getter methods of the ResultSet interface (getInt(), getString(), getDate() etc..).To retrieve required data from a table:Connect to the database.Create a Statement object.Execute the Statement using the executeQuery() method. To this method, pass the select query in the String format. To retrieve all the values, we use the following query:Select ... Read More

A ResultSet interface in JDBC represents the tabular data generated by SQL queries. It has a cursor which points to the current row. Initially, this cursor is positioned before the first row.Moving the pointer throughout result setThe next() method of the ResultSet interface moves the pointer of the current (ResultSet) object to the next row, from the current position. This method returns a boolean value, if there are no rows next to its current position it returns false, else it returns true. Therefore, using this method in the while loop you can iterate the contents of the result set.while(rs.next()){ }Getting the ... Read More

Following are the main differences between functions and procedures:FunctionsProceduresA function has a return type and returns a value.A procedure does not have a return type. But it returns values using the OUT parameters.You cannot use a function with Data Manipulation queries. Only Select queries are allowed in functions.You can use DML queries such as insert, update, select etc… with procedures.A function does not allow output parametersA procedure allows both input and output parameters.You cannot manage transactions inside a function.You can manage transactions inside a procedure.You cannot call stored procedures from a functionYou can call a function from a stored procedure.You ... Read More

Like procedures, you can also create function in a database and store them.SyntaxFollowing is the syntax of creating a function in a(MySQL) database:CREATE FUNCTION Function_Name(input_arguments) RETURNS output_parameter BEGIN    declare variables;    statements . . . . . . . . . .    return data_type;    ENDExampleSuppose we have a table named Emp in the database with the following content:+--------+------------+----------------+ | Name   | DOB        | Location      | +--------+------------+----------------+ | Amit   | 1970-01-08 | Hyderabad      | | Sumith | 1970-01-08 | Vishakhapatnam | | Sudha  | 1970-01-05 | Vijayawada     ... Read More

Stored procedures are sub routines, segment of SQL statements which are stored in SQL catalog. All the applications that can access Relational databases (Java, Python, PHP etc.), can access these procedures.Stored procedures contain IN and OUT parameters, or both. They may return result sets in case you use SELECT statements, they can return multiple result-sets.ExampleSuppose we have a table named Dispatches in the MySQL database with the following data:+--------------+------------------+------------------+------------------+ | Product_Name | Date_Of_Dispatch | Time_Of_Dispatch | Location         | +--------------+------------------+------------------+------------------+ | KeyBoard     | 1970-01-19       | 08:51:36         | Hyderabad ... Read More

Following are the advantages of the prepared statement:By avoiding multiple compilation and execution of statements, prepared statements perform faster.Using prepared statements, we can insert values to advanced datatypes such as BLOB, CLOB, OBJECT easily with the help of the setter methods provided by the PreparedStatement interface.By providing setter method to set values prepared statement avoids the use of quotes and other special characters with in the query, and thereby it escapes the SQL injection attacksFollowing are the limitations of prepared statements:Since a PreparedStatement object represents only one SQL statement at a time, we can execute only one statement by one ... Read More

While executing statements using Statement object, especially insert statements, each time a query is executed the whole statement is compiled and executed again and again where, the only difference among these statements is the values of the statements.Whereas, prepared statement is a precompiled statement i.e. the query is compiled and stored in the database, using place holders (?) instead of values and values to these place holders are supplied later.Thus, avoiding unnecessary compilation and execution of the statement again and again.ExampleSuppose, we have a table named Dataset in the database with the columns mobile_brand and unit_sale, if we want to ... Read More