what is the difference between cursor and ref cursor in oracle?
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The ref cursor can be anything. ... a plsql "cursor cursor" cannot be returned to a client. Another difference is a cursor can be global -- a ref cursor cannot (you cannot define them OUTSIDE of a procedure / function) Another difference is a ref cursor can be passed from subroutine to subroutine -- a cursor cannot be.
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The ref keyword on a method parameter causes a method to refer to the same variable that was passed as an input parameter for the same method. ... The out parameter can be used to return the values in the same variable passed as a parameter of the method. Any changes made to the parameter will be reflected in the variable.
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['SQLLOADER. sqlloader is an Oracle utility to load data from external files to table. ... ', 'EXTERNAL TABLES. External tables is an advanced feature of Oracle SQLLOADER. ... ', 'UTL. UTL is another Oracle utility to load data from flat file to Oracle and vice versa. ... ', 'Using Tools (SQLDEVELOPER) EMP. ... ', 'INSERT script.']
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SQL statements are called from PL/SQL in a loop, so the execution will switch back and forth between the PL/SQL engine and the SQL engine. This switch between two environments is known as a context switch. Context switches increase elapsed time of your programs and introduce unnecessary CPU overhead.
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There are two forms of ref Cursor the strong REF CURSOR and the weak REF CURSOR. PL/SQL is a statically typed language, and the weak REF CURSOR is one of the few dynamically typed constructs supported. When you defined a SYS_REFCURSOR is a predefined weak REF CURSOR type.
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A ref cursor is a pointer to a result set. This is normally used to open a query on the database server, then leave it up to the client to fetch the result it needs. A ref cursor is also a cursor, though normally ther term cursor is used when discussing static SQL. Static cursor is associated with single SQL query.
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A function or procedure is a set of instructions to perform some task. A cursor is an array that can stores the result set of a query. Stored procedures are pre-compiled objects and executes as bulk of statements, whereas cursors are used to execute row by row.
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ref specifies that the value is a reference that has a value, and whose value you can change inside the method. out parameters are initialized by the method called, ref parameters are initialized before calling the method.
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There are a few differences between the Oracle GREATEST and MAX functions: Both MAX and GREATEST will return one result, but MAX is an aggregate function and GREATEST is not. GREATEST can return multiple rows. It will return one row for each row of data you query as it is not an aggregate function.
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A procedure does not return a value. Instead, it is invoked with a CALL statement to perform an operation such as modifying a table or processing retrieved records. On the other hand, a function is invoked within an expression and returns a single value directly to the caller to be used in the expression.
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Hope this simple tip help. One other trick for those who want to comment in and out a lot of lines is to use ctrl + / . That will comment out either the line that your cursor is on, or whatever lines you have highlighted. You can then highlight the lines and use ctrl + / again to un-comment them.
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['NOT NULL - Ensures that a column cannot have a NULL value.', 'UNIQUE - Ensures that all values in a column are different.', 'PRIMARY KEY - A combination of a NOT NULL and UNIQUE. ... ', 'FOREIGN KEY - Uniquely identifies a row/record in another table.']
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Creating a database using python You can create a cursor object using the cursor() method of the Connection class. The execute() method of this class accepts a PostgreSQL query as a parameter and executes it. Therefore, to create a database in PostgreSQL, execute the CREATE DATABASE query using this method.
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Cursors In SQL Server. Cursor is a database object to retrieve data from a result set one row at a time, instead of the T-SQL commands that operate on all the rows in the result set at one time. We use a cursor when we need to update records in a database table in singleton fashion means row by row.
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The main difference between undo and redo in Oracle is that undo helps in rollback and maintaining read consistency while redo helps in rolling forward database changes. ... Overall, undo and redo are records available in Oracle RDBMS. Undo is a record of a transaction before it is committed.
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['CREATE – is used to create the database or its objects (like table, index, function, views, store procedure and triggers).', 'DROP – is used to delete objects from the database.', 'ALTER-is used to alter the structure of the database.']
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Introduction to MySQL cursor To handle a result set inside a stored procedure, you use a cursor. A cursor allows you to iterate a set of rows returned by a query and process each row individually. ... Non-scrollable: you can only fetch rows in the order determined by the SELECT statement.