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MySQLi Articles
Page 270 of 341
Why are Prepared Statements in JDBC faster than Statements? Explain?
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 MoreHow many locking systems are there in JDBC?
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 MoreWhat are the important methods of the SQLException class?
An SQLException can occur both in the driver and the database. When such an exception occurs, an object of type SQLException will be passed to the catch clause.The passed SQLException object has the following methods available for retrieving additional information about the exception:MethodDescriptiongetErrorCode( )Gets the error number associated with the exception.getMessage( )Gets the JDBC driver's error message for an error, handled by the driver or gets the Oracle error number and message for a database error.getSQLState( )Gets the XOPEN SQLstate string. For a JDBC driver error, no useful information is returned from this method. For a database error, the five-digit ...
Read MoreCan we call functions using Callable Statements? Explain with an example in JDBC?
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 MoreWhat is JDBC SQL Escape Syntax Explain?
The escape syntax gives you the flexibility to use database specific features unavailable to you by using standard JDBC methods and properties.The general SQL escape syntax format is as follow:{keyword 'parameters'}Following are various escape syntaxes in JDBC:d, t, ts Keywords: They help identify date, time, and timestamp literals. As you know, no two DBMSs represent time and date the same way. This escape syntax tells the driver to render the date or time in the target database's format{d 'yyyy-mm-dd'}Where yyyy = year, mm = month; dd = date. Using this syntax {d '2009-09-03'} is March 9, 2009.Example//Create a Statement object ...
Read MoreWhat is DatabaseMetaData in JDBC? What is its significance?
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 MoreWhat is the use of the method setAutoCommit() in JDBC?
If you commit a database, it saves all the changes that have been done till that particular point.You can commit a database using the commit() method. Whenever any issue occurs you can revert the database to this point using the rollback() method. By default, some databases commit the databases automatically. But, while managing transactions you need to commit the database manually.In this scenario you can use the setAutoCommit() method. This method belongs to the Connection interface and, it accepts a boolean value.If you pass true to this method it turns on the auto-commit feature of the database and, if you ...
Read MoreWhat is the difference between the methods setBlob() and setBinaryStream() which is preferable in JDBC?
The setBlob() method is used to set value for Blob datatype in the database. It has three variants as follows:void setBlob(int parameterIndex, Blob x): Sets the given Blob value to the parameter at the specified index.void setBlob(int parameterIndex, InputStream inputStream): Sets the contents of the given input stream as a value to the parameter at the specified index.void setBlob(int parameterIndex, InputStream inputStream, long length): Sets the contents of the given input stream as a value to the parameter at the specified index.The setBinaryStream() method is used to set the contents of the given InputStream as a value for the parameter ...
Read MoreHow many types of Result Sets are there in JDBC What are they?
There are two types of result sets namely, forward only and, bidirectional.Forward only ResultSet: The ResultSet object whose cursor moves only in one direction is known as forward only ResultSet. By default, JDBC result sets are forward-only result sets.You can move the cursor of the forward only ResultSets using the next() method of the ResultSet interface. It moves the pointer 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 ...
Read MoreHow to insert images in Database using JDBC?
The setBinaryStream() method of the PreparedStatement interface accepts an integer representing the index of the parameter and an InputStream object and sets the parameter to the given InputStream object. Whenever you need to send very large binary value you can use this method.And SQL databases provide a datatype named Blob (Binary Large Object) in this you can store large binary data like images.Storing image using JDBCIf you need to store an image in a database using the JDBC program create a table with a Blob datatype as shown below:CREATE TABLE Tutorial(Name VARCHAR(255), Type INT NOT NULL, Logo BLOB);Now, using JDBC, connect ...
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