Employee-table.png' alt='Java Preparedstatement Select For Update Syntax' title='Java Preparedstatement Select For Update Syntax' />Generate large EXCEL in java using Apache POI SXSSF implementation and avoid java.Out. Of. Memory. Error.Note SXSSF is a brand new contribution, features are still being added after it was first introduced in POI 3.Users can to try the latest build from trunk or take the latest beta version.Since 3. POI provides a low memory footprint SXSSF API built on top of XSSF.SXSSF is an API compatible streaming extension of XSSF to be used when very large spreadsheets have to be produced, and heap space is limited.SXSSF achieves its low memory footprint by limiting access to the rows that are within a sliding window, while XSSF gives access to all rows in the document.Older rows that are no longer in the window become inaccessible, as they are written to the disk.In auto flush mode the size of the access window can be specified, to hold a certain number of rows in memory.When that value is reached, the creation of an additional row causes the row with the lowest index to to be removed from the access window and written to disk.Or, the window size can be set to grow dynamically it can be trimmed periodically by an explicit call to flush.Rowsint keep. Rows as needed.Due to the streaming nature of the implementation, there are the following limitations when compared to XSSF Only a limited number of rows are accessible at a point in time.Sheet. clone is not supported.Formula evaluation is not supported.Tip If your are getting Exception in thread main java.PreparedStatement-batch-update-database-query.png' alt='Java Preparedstatement Select For Update Syntax' title='Java Preparedstatement Select For Update Syntax' />Out.Of. Memory. Error Java heap space, then you must use the low memory footprint SXSSF API implementation.Sample Java code implementing Apache POI to Generate very large Excel from any database.In the example below I am connecting to the Db.Series or currently named as IBM i.You can change the database connection to SQL server, MYSQL, Oracle etc.The following jars are needed to execute the sample code.Note You need Java 1.File. Input. Stream.File. Output. Stream.Print. Stream. import java.Connection. import java.Driver. Manager. import java.Prepared. Statement.Result. Set. import java.Result. Set. Meta.Data. import java.Iterator. import java.Linked. Hash. Map.Properties. import org.Java Preparedstatement Select For Update Syntax' title='Java Preparedstatement Select For Update Syntax' />I have a general Java method with the following method signature private static ResultSet runSQLResultSetString sql, Object.Params It opens a connection.Steve Friedls Unixwiz.Tech Tips SQL Injection Attacks by Example.A JDBC tutorial for executing basic SQL statements like INSERT, SELECT,UPDATE and DELETE.Java API. Now that you know how to configure MyBatis and create mappings, youre ready for the good stuff.The MyBatis Java API is where you get to reap the rewards.SXSSFWorkbook. import org.SXSSFSheet. import org.XSSFCell. Style. import org.Cell. import org.Cell. Style. import org.Data. Format. import org.Font. import org.Indexed. Colors. import org.Row. import org. apache.Workbook. public class Database.To. Excel. 3. static Properties props.String args. String excel.Filename null. String sql.String null. Database.To. Excel. 3 database.To. Excel. 3 new Database.To. Excel. 3. if args.System. err. printlnUsage java database.To. Excel. 3. get.Class. get. Name.ExcelFilename SqlSelectString.System. exit1. excel.Filename args0. String args1.To. Excel. 3. generate.Excelsql. String, excel.Filename. public void generate.ExcelString sql. String, String excel.Filename. Print. Stream p new Print.Streamnew File. Output.Stream dataerror.System. set. Outp.Properties. props.File. Input. Streampropertiesdataconnection.String DRIVER com.AS4. 00. JDBCDriver.String URL jdbc as.Propertylocalsystem.Connection conn null.String sql null. Prepared.Statement stmt null.Connect to i. Series.Class. for. NameDRIVER.Driver. Manager. get.ConnectionURL,props.Propertyuser. Id.Propertypassword.New Workbook. Workbook wb new SXSSFWorkbook.Cell c null. Cell style for header row.Cell. Style cs wb.Cell. Style. cs. Fill.Foreground. ColorIndexed.Colors. LIME. get.Index. Fill. PatternXSSFCell.Style. SOLIDFOREGROUND.Font f wb. create.Font. f. set. BoldweightFont.BOLDWEIGHTBOLD. Font.Height. In. Pointsshort 1.Fontf. New Sheet.SXSSFSheet sheet.SXSSFSheet wb. create.Sheetmy. Data. String.Statementsql. Result.Set rs stmt. execute.Query. Result. Set.Meta. Data meta. Data rs.Meta. Data. int col.Count meta. Data.Column. Count. Create Hash Map of Field Definitions.Linked. Hash. Maplt Integer, My.Table. Info hash.Map new Linked. Hash.Maplt Integer, My.Table. Info col. Count.Count i. My. Table.Info db. 2Table. Info new My.Table. Info. db. 2Table.Info. set. Field.Namemeta. Data. get.Column. Namei 1. Table.Info. set. Field.Textmeta. Data. get.Column. Labeli 1.Table. Info. set.Field. Sizemeta. Data.Precisioni 1. Table.Info. set. Field.Decimalmeta. Data.Scalei 1. Table. Info.Field. Typemeta. Data.Column. Typei 1. db.Table. Info. set.Cell. Styleget. Cell.Attributeswb, c, db.Table. Info. hash.Map. puti, db. 2Table.Info. Row and column indexes.Generate column headings.Row row sheet. 1.Rowidx. My. Table.Info db. 2Table. Info new My.Table. Info. Iteratorlt Integer iterator hash.Map. key. Set. iterator.Next. Integer key Integer iterator.Table. Info hash.Map. getkey. c row.Cellidy. c. set. Cell.Valuedb. 2Table. Info.Field. Text. c. set.Cell. Stylecs. ifdb.Table. Info. get.Field. Size db. Table.Info. get. Field.Text. trim. Column.Widthidy, db. Table.Info. get. Field.Size 5. Column. Widthidy, db.Table. Info. get.Field. Text. trim.Rowidx. System. Count i.Celli. db. 2Table.Info hash. Map. Table.Info. get. Field.Type. Cell. Valuers.Stringi1. break. Cell.Valuers. get. Doublei1.Cell. Valuers. get.Doublei1. break. Cell.Valuers. get. Stringi1.Cell. Styledb. 2Table.Info. get. Cell. Style.File. Output. Stream file.Out new File. Output.Streamprops. get.Propertyexcelpath.Filename. trim. Out.Out. close. Exception e.System. Cell. Style get.Cell. Attributes Workbook wb, Cell c, My.Table. Info db. 2Table.Info. Cell. Style cs wb.Cell. Style. Data.Format df wb. create.Data. Format. Font f wb.Font. switch db. Table.Info. get. Field.Decimal. Data. Formatdf.Format,0. 0. Data.Formatdf. get. Format,0.Data. Formatdf. get.Format,0. 0. Data.Formatdf. get. Format,0.Data. Formatdf. get.Format,0. 0. Fontf.Source code for My.Table. Info. javapackage com.Cell. Style. public class My.Table. Info. String field.Name null. String field.Text null. int field.Type 0. int field.Size 0. int field.Decimal 0. Cell. Style cell.Style null. String get.Field. Name. return field.Name. public void set.Field. NameString field.Name. this. field.Name field. Name.String get. Field.Text. return field.Text. public void set.Field. TextString field.Text. this. field.Text field. Text.Field. Type. return field.Type. public void set.Field. Typeint field.Type. this. field.Type field. Type.Field. Size. return field.Size. public void set.Field. Sizeint field.Size. this. field.Size field. Size.Field. Decimal. Decimal.Field. Decimalint field.Decimal. this. Decimal field.Decimal. Cell. Style get.Cell. Style. return cell.Style. public void set.Cell. StyleCell. Style cell.Style. Style cell.Style. Sample for dataconnection.I series ip or host name.I series User. Id, used for login and library list.Idyouruserid. I series Password.Path for EXCEL data.Recommended Reading.SQL Insert, Select, Update, and Delete Examples.Details Last Updated on 0.August 2. 01. 7 Print Email.This tutorial is going to help you learning how to do basic database operations CRUD Create, Retrieve, Update and Delete using JDBC Java Database Connectivity API.These CRUD operations are equivalent to the INSERT, SELECT, UPDATE and DELETE statements in SQL language.Although the target database system is My.SQL, but the same technique can be applied for other database systems as well because the query syntax used is standard SQL which is supported by all relational database systems.We will learn how to do insert, query, update and delete database records by writing code to manage records of a table Users in a My.SQL database called Sample.DB. Table of content Prerequisites.Creating a sample My.SQL database. The principal JDBC interfaces and classes.Connecting to the database.Executing INSERT statement.Executing SELECT statement.Executing UPDATE statement.Executing DELETE statement.Prerequisites To begin, make sure you have the following pieces of software installed on your computer 2.Creating a sample My.SQL database Lets create a My.SQL database called Sample.DB with one table Users with the following structure Execute the following SQL script inside My.SQL Workbench create database Sample.DB. CREATE TABLE users.NOT NULL AUTOINCREMENT.NOT NULL. password varchar4.NOT NULL. fullname varchar4.NOT NULL. email varchar4.NOT NULL. PRIMARY KEY userid.Or if you are using My.SQL Command Line Client program, save the above script into a file, lets say, SQLScript.PathToTheScriptFileSQLScript.Heres an example screenshot taken while executing the above script in My.SQL Command Line Client program 3.The principal JDBC interfaces and classes Lets take an overview look at the JDBCs main interfaces and classes with which we usually work.They are all available under the java.Driver. Manager this class is used to register driver for a specific database type e.My. SQL in this tutorial and to establish a database connection with the server via its get.Connection method.Connection this interface represents an established database connection session from which we can create statements to execute queries and retrieve results, get metadata about the database, close connection, etc.Statement and Prepared.Statement these interfaces are used to execute static SQL query and parameterized SQL query, respectively.Statement is the super interface of the Prepared.Statement interface.Their commonly used methods are boolean executeString sql executes a general SQL statement.It returns true if the query returns a Result.Set, false if the query returns an update count or returns nothing.This method can be used with a Statement only.UpdateString sql executes an INSERT, UPDATE or DELETE statement and returns an update account indicating number of rows affected e.Result. Set execute.QueryString sql executes a SELECT statement and returns a Result.Set object which contains results returned by the query.A prepared statement is one that contains placeholders in form question marks for dynamic values will be set at runtime.For example SELECT from Users WHERE userid Here the value of userid is parameterized by a question mark and will be set by one of the set.XXX methods from the Prepared.Statement interface, e.Intint index, int value.Result. Set contains table data returned by a SELECT query.Use this object to iterate over rows in the result set using next method, and get value of a column in the current row using get.XXX methods e. String, get.Int, get. Float and so on.The column value can be retrieved either by index number 1 based or by column name.SQLException this checked exception is declared to be thrown by all the above methods, so we have to catch this exception explicitly when calling the above classes methods.Practical Database Programming with Java This book is for those who are beginner in Java database programming and want to catch up with the main database programming techniques with straightforward and easy to learn example code.Connecting to the database Supposing the My.SQL database server is listening on the default port 3.The following code snippet connects to the database name Sample.DB by the user root and password secret String db.URL jdbc mysql localhost 3.String username root. Microsoft Office Word 2003 Full Trial Versions . String password secret.Connection conn Driver.Manager. get. Connectiondb.URL, username, password.System. out. printlnConnected.SQLException ex. Stack.Trace. Once the connection was established, we have a Connection object which can be used to create statements in order to execute SQL queries.In the above code, we have to close the connection explicitly after finish working with the database conn.However, since Java 7, we can take advantage of the try with resources statement which will close the connection automatically, as shown in the following code snippet try Connection conn Driver.Manager. get. Connectiondb.URL, username, password.SQL queries goes here.SQLException ex. Stack.Trace. If you are using Java 7 or later, this approach is recommended.The sample programs in this tutorial are all using this try with resources statement to make a database connection.NOTE For details about connecting to a My.SQL database, see the article Connect to My.SQL database via JDBC.Executing INSERT statement Lets write code to insert a new record into the table Users with following details username billpassword secretpassfullname Bill Gatesemail bill.Heres the code snippet String sql INSERT INTO Users username, password, fullname, email VALUES, ,.Prepared. Statement statement conn.Statementsql. statement.String1, bill. String2, secretpass.String3, Bill Gates.String4, bill. gatesmicrosoft.Inserted statement.Update. if rows. Inserted 0.System. out. printlnA new user was inserted successfully.In this code, we create a parameterized SQL INSERT statement and create a Prepared.Statement from the Connection object.To set values for the parameters in the INSERT statement, we use the Prepared.Statements set. String methods because all these columns in the table Users are of type VARCHAR which is translated to String type in Java.Note that the parameter index is 1 based unlike 0 based index in Java array.The Prepared. Statement interface provides various set.XXX methods corresponding to each data type, for example set.Booleanint parameter.Index, boolean xset.Dateint parameter.Index, Date xset.Floatint parameter.Index, float x And so on.Which method to be used is depending on the type of the corresponding column in the database table.Finally we call the Prepared.Statements execute.Update method to execute the INSERT statement.This method returns an update count indicating how many rows in the table were affected by the query, so checking this return value is necessary to ensure the query was executed successfully.In this case, execute.Update method should return 1 to indicate one record was inserted.Recommended Book Getting Started with No.SQL6. Executing SELECT statement The following code snippet queries all records from the Users table and print out details for each record String sql SELECT FROM Users.Statement statement conn.Statement. Result.Set result statement.Querysql. while result.String name result.String2. String pass result.String3. String fullname result.Stringfullname. String email result.Stringemail. String output User d s s s s.System. out. printlnString.Output User 1 bill secretpass Bill Gates bill.Because the SQL SELECT query here is static so we just create a Statement object from the connection.The while loop iterates over the rows contained in the result set by repeatedly checking return value of the Result.Sets next method.The next method moves a cursor forward in the result set to check if there is any remaining record.For each iteration, the result set contains data for the current row, and we use the Result.Sets get. XXXcolumn indexcolumn name method to retrieve value of a specific column in the current row, for example this statement String name result.String2. Retrieves value of the second column in the current row, which is the username field.
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