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An SQL UPDATE statement changes the data of one or more records in a table. Either all the rows can be updated, or a subset may be chosen using a condition. The UPDATE statement has the following form: [1] UPDATE table_name SET column_name = value [, column_name = value ...] [WHERE condition]
In order to retrieve the desired data the user presents a set of criteria by a query. Then the database management system selects the demanded data from the database. The retrieved data may be stored in a file, printed, or viewed on the screen. A query language, like for example Structured Query Language (SQL), is used to prepare the queries.
The command object can send SQL queries directly to the provider through the use of the CommandText property, send a parameterised query or stored procedure through the use of a Parameter object or Parameters collection or run a query and return the results to a dataset object via the Execute method. There are several other methods that can be ...
In SQL, the data manipulation language comprises the SQL-data change statements, [3] which modify stored data but not the schema or database objects. Manipulation of persistent database objects, e.g., tables or stored procedures, via the SQL schema statements, [3] rather than the data stored within them, is considered to be part of a separate data definition language (DDL).
The data are updated at the data source after the record is changed and the Update method is called. Batch The recordset is locked using adLockBatchOptimistic and each time Update is called the data are updated in a temporary buffer. Finally, when UpdateBatch is called the data are completely updated back at the data source.
Jet passes the data retrieved for the query in a dynaset. This is a set of data that is linked dynamically back to the database. Instead of having the query result stored in a temporary table, where the data cannot be updated directly by the user, the dynaset allows the user to view and update the data contained in the dynaset.
Update statements such as INSERT, UPDATE and DELETE return an update count indicating the number of rows affected in the database as an integer. [13] These statements do not return any other information. Query statements return a JDBC row result set. The row result set is used to walk over the result set.
Queries, which retrieve the data based on specific criteria. This is an important element of SQL. Statements, which may have a persistent effect on schemata and data, or may control transactions, program flow, connections, sessions, or diagnostics. SQL statements also include the semicolon (";") statement terminator. Though not required on ...