How to understand the transaction functions transaction and executeSQL in html5 Web SQL Database

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1. After you create or open the database, you can use the transaction API transaction. Each transaction, as an atomic operation that operates the database, is not interrupted, thus avoiding data conflicts. Transaction is defined as:

The code is as follows:

Void transaction (querysql, errorCallback, successCallback)

Querysql: the transaction callback function, where the SQL statement can be executed. (required)

ErrorCallback: error callback function. (optional)

SuccessCallback: execute the callback function successfully. (optional)

2. In the callback function querysql, you can execute the SQL statement. The corresponding API function is defined as executeSQL,executeSQL:

The code is as follows:

Void executeSql (sqlStatement, arguments, callback, errorCallback)

SqlStatement:SQL statement. (required)

The parameters required by the arguments:SQL statement are those in the sql statement. An one-dimensional array arranged sequentially. (optional)

Callback: callback function. (optional)

ErrorCallback: error callback function. (optional)

Web SQL Database example

Here is an example to illustrate the basic use of Web SQL Database. It first calls openDatabase to create a database called "fooDB". Then use transaction to execute two SQL statements. The first SQL statement creates a table named "foo", and the second SQL statement inserts a record into the table. Sample code:

The code is as follows:

Var db = openDatabase ('fooDB',' 1.0, 'fooDB', 2 * 1024)

Db.transaction (function (tx) {

Tx.executeSql ('CREATE TABLE IF NOT EXISTS foo (id unique, text)')

Tx.executeSql ('INSERT INTO foo (id, text) VALUES (1, "foobar"))

});

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