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JDBC Articles
Page 15 of 22
How do I check to see if a column name exists in a CachedRowSet in JDBC?
CachedRowSet interface does not provide any methods to determine whether a particular column exists.Therefore, to find whether a RowSet contains a specific column, you need to compare the name of each column in the RowSet with the required name. To do so −Retrieve the ResultSetMetaData object from the RowSet using the getMetaData() method.ResultSetMetaData meta = rowSet.getMetaData();Get the number of columns in the RowSet using the getColumnCount() method.int columnCount = meta.getColumnCount();The getColumnName() method returns the name of the column of the specified index. Using this method retrieve the column names of the RowSet from index 1 to column count and compare ...
Read MoreHow to start a transaction in JDBC?
A transaction is a unit of work that is performed against a database. Transactions are units or sequences of work accomplished in a logical order, whether in a manual fashion by a user or automatically by some sort of a database program.A transaction is the propagation of one or more changes to the database. For example, if you are creating a record or updating a record or deleting a record from the table, then you are performing a transaction on that table. It is important to control these transactions to ensure the data integrity and to handle database errors.Ending a ...
Read MoreHow to get LocalDateTime object from java.sql.Date using JDBC?
The java.time package of Java8 provides a class named LocalDateTime is used to get the current value of local date and time. Using this in addition to date and time values you can also get other date and time fields, such as day-of-year, day-of-week and week-of-year.Converting java.sql.Date to LocalDateTimeThe java.sql.TimeStamp class provides a method with name toLocalDateTime() this method converts the current timestamp object to a LocalDateTime object and returns it.To convert date to LocalDateTime object.Create a Timestamp object from Date object using the getTime() method as −Date date = rs.getDate("DispatchDate"); //Converting Date to Timestamp Timestamp timestamp = new Timestamp(date.getTime());Now, ...
Read MoreHow to retrieve a DATALINK object from a table using JDBC?
A DATALINK object represents an URL value which refers to an external resource (outside the current database/data source), which can be a file, directory etc..You can retrieve a DATALINK object an SQL table using the getURL() method of the PreparedStatement interface. This method accepts an integer value representing an index of the column in the ResultSet and returns the URL object in the specified index.ExampleLet us create a table with name tutorials_data in MySQL database using CREATE statement as shown below −CREATE TABLE tutorials_data ( tutorial_id INT PRIMARY KEY AUTO_INCREMENT, tutorial_title VARCHAR(100), tutorial_author VARCHAR(40), submission_date date, ...
Read MoreWrite a program to get the list of all the supported datatypes in JDBC?
The class named Types of the java.sql package contains the constants that represents the SQL datatypes. All these datatypes are represented by unique integer values.Retrieving the integer values from the Types classTo print all the class names and values of the constants in java.sql.Types class −Retrieve all the fields in Types class − The getFields() method of the class Class returns an array which holds all the fileds (public) of the class/interface represented by the current Class object.Using this method retrieve the array of fileds of the Types class as shown below −Field[] fields = java.sql.Types.class.getFields();Retrieve the name and value ...
Read MoreHow to create a MySQL table based on JDBC Result Set?
The ResultSetMetadata class provides various methods that gives information about the current ResultSet object such as number of columns, name of the table, name of the column, datatype of the column etc…To prepare a CREATE query you need to get −Name of the table, using the getTableName() method.Column count, to iterate the columns using the getColumnCount() method.Name of the each column using the getColumnName() method.Data type of each column using the getColumnTypeName() method.Precision of each column using the getPrecision() method.ExampleLet us create a table with name customers in MySQL database using the CREATE query as shown below −CREATE TABLE Customers ...
Read MoreHow to insert Binary data into a table using JDBC?
SQL databases provide a datatype named Blob (Binary Large Object) in this, you can store large binary data like images.To store binary (stream) values into a table JDBC provides a method called setBinaryStream() in the PreparedStatement interface.It accepts an integer representing the index of the bind variable representing the column that holds values of type BLOB, an InputStream object holding the binary data and, inserts the given data in to the specified column.You can insert binary stream data into a table using this method as shown below −FileInputStream fin = new FileInputStream("javafx_logo.jpg"); pstmt.setBinaryStream(3, fin);ExampleLet us create a table with name ...
Read MoreHow to retrieve binary data from a table using JDBC?
SQL databases provide a datatype named Blob (Binary Large Object) in this, you can store large binary data like images.To retrieve binary (stream) values from a table JDBC provides a method called getBinaryStream() in the PreparedStatement interface.It accepts an integer representing the index of the column of the table and retrieves the binary data from it.You can retrieve binary data from a table using this method as shown below −FileInputStream fin = new FileInputStream("javafx_logo.jpg"); pstmt.setBinaryStream(3, fin);ExampleLet us create a table with name tutorials_data in MySQL using the CREATE statement as shown below −CREATE TABLE tutorials_data( Name VARCHAR(255), Type ...
Read MoreHow to get the properties of a driver using JDBC?
You can get the properties of a driver using the getPropertyInfo() method of the Driver interface.DriverPropertyInfo[] info = driver.getPropertyInfo(mysqlUrl, null);This method accepts a two parameters: A String variable representing the URL of the database, an object of the class Properties and, returns an array of the DriverPropertyInfo objects, where each object holds information about the possible properties of the current driver.From a DriverPropertyInfo object you can get the information such as name of the property, value of the property, description, choices and, if it is required or not, using its fields name, value, description, choices, required, respectively.DriverPropertyInfo[] info = driver.getPropertyInfo(mysqlUrl, ...
Read MoreHow to Read data from BLOB and CLOB type columns from a table using JDBC?
Clob datatypeCLOB stands for Character Large Object. in general, an SQL Clob is a built-in datatype which is used to store large amount of textual data. Using this datatype, you can store data up to 2, 147, 483, 647 characters. MYSQL database provides support Clob datatype TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT.The java.sql.Clob interface of the JDBC API represents the CLOB datatype. Since the Clob object in JDBC is implemented using an SQL locator, it holds a logical pointer to the SQL CLOB (not the data).Reading Data from a column of datatype ClobYou can read CLOB value (character stream data) from a ...
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