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Introduction to Database Transactions A database transaction is a logical unit of work that consists of a set of SQL statements. You can think of a transaction as an irreducible set of SQL statements that are permanently recorded in the database or

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1. Object definition When the Create command is executed to create an object, Oracle stores the object definition in the data dictionary. 03:31:40 sql> Select Dbms_metadata.get_ddl (' TABLE ', ' DEPT ') DDL from DUAL; Ddl ------------------------

The error of indexing using indexes six: indexing all columns We know that indexing is an effort to improve query efficiency, but it should also be noted that indexes increase the cost of DML operations (INSERT, UPDATE, delete), and that most

Oracle Table Connection Overview: Sql/oracle Use table joins to query data from multiple tables Format: Select field list from Table1,table2 where Table1.column1=table2.column2; Note: When the same name field exists in multiple tables that are

Oracle Introduction to Database Transactions A database transaction is a logical unit of work that consists of a set of SQL statements. You can think of a transaction as an irreducible set of SQL statements that are permanently recorded in the

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Design | data | database | Database Design relational database design is to follow certain rules. In particular, database design paradigm is briefly introduced 1NF (first normal form), 2NF (second normal form), 3NF (third normal form) and BCNF,

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1. Definition Process: (1) Accept 0 or more parameters as input (input) or output (outputs), or both as input and output (INOUT). (2) Unlike functions, stored procedures do not return a value. (3) Stored procedures cannot be used directly by SQL

To use the Pl/sql program to complete a more complete database task, you need to further learn some advanced design elements of the content. The Pl/sql program that was written earlier, common to the absence of names, can only be stored as files,

Oracle Oracle's Sql*plus is a client tool that interacts with Oracle. In Sql*plus, you can run the Sql*plus command and the Sql*plus statement. Our usual DML, DDL, and DCL statements are sql*plus statements that, when executed, can be stored in an

A relational database is designed to conform to certain rules. In particular, database design paradigm is briefly introduced 1NF (first normal form), 2NF (second normal form), 3NF (third normal form) and BCNF, another fourth normal form and fifth

There is a d_alloc function in the kernel that allocates a dentry structure and initializes it. /*** D_alloc-allocate a Dcache entry* @parent: Parent of entry to allocate* @name: Qstr of the name** Allocates a dentry. It returns%null if there is

Two myths about indexing using indexes: Using the <> and!= operators, causing queries to not use indexes First of all, please remember this conclusion: The index is not used after <> and!= are used For example, the following example uses Select

Insert statement Syntax: INSERT into table [(Column1, Column2 ...)] VALUES (value1, value2 ...); Description: INSERT statement inserts a record into the table at a time. When the default field Name list is listed, you should explicitly set the new

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oracle| Create | page Create an HTML page with Oracle's Sql*plus tool Author: fenng Oracle's Sql*plus tools have some interesting options, reasonable use, can give us unexpected consequences. One of the "-M" options can be created to create

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Workaround for UNIX training: we might as well make a workaround. The row-level trigger is adapted to a statement-level trigger. Look at the following processing. 1. Create a package:emp_pkg. CREATE Orreplace PACKAGE emp_pkg as /* ----------------