Oracle和MIcrosoftSQL的不同

还是有很多的不同,转贴如下:http://www.bristle.com/Tips/SQL.htm#Oracle%20Tips

Table of Contents:

Details of Tips:

1. Oracle Tips

   1. SQL Tips

      This section contains tips on standard SQL (Structured Query Language) statements in Oracle.

      1. SELECT * and more

         Last Updated: 6/6/1999
         Applies to:  Oracle 7.3, 8 (and probably earlier versions)

         To select all columns of a table:

         	select * from table

         However, to select all real columns, plus a pseudo-column like "user":

         	select table.*, user from table

         The following does not work:

         	select *, user from table

         --Fred

      2. Materialized View

         Last Updated: 1/7/2002
         Applies to:  Oracle 8+

         Oracle 8i introduced a new feature called a "materialized view".  You define it just like any other view, except that you add the keyword MATERIALIZED:

         	CREATE MATERIALIZED VIEW view_name

         A materialized view is like a combination of a table and a view.  Like a view, it is defined as a logical view into the data of one or more tables.  When you update the tables, subsequent queries of the view see the updated data.  However, like a table, its data is stored in the database.  Also, like a table, it is faster if you define indexes for it.

         A regular view is stored as a mapping of data from tables.  When you modify the data in the tables, the view is completely ignored.  When you aclearcase/" target="_blank" >ccess the view, it joins the data currently in the tables, and returns the data you requested.  A materialized view is stored as such a mapping along with a copy of the actual data from the tables.  When you modify the data in the tables, the view's copy of the data is also updated.  When you access the view, the data is drawn directly from the copy.

         Thus a materialized view makes table updates a little slower, but makes view queries much faster.  It also consumes additional space in the database.

         You could accomplish the same effect by defining an additional table instead of the view, and using triggers on the component tables to update it each time they are changed.  However, using a materialized view is more convenient, more efficient, and clearer to the next person who has to maintain your database.

         Thanks to Andy Glick for sending me a sample of a materialized view from his application!

         --Fred

   2. PL/SQL Tips

      This section contains tips on PL/SQL statements -- the Oracle "procedural language" superset of SQL that you use to write stored procedures.

   3. SQL Navigator Tips

      This section contains tips on the SQL Navigator tool by Quest Systems. It is a graphical front end to the Oracle database, allowing you to create, delete, view, and modify all Oracle objects: tables, views, stored procedures, etc.

   4. See Also

      Last Updated: 6/6/1999
      Applies to:  Oracle 7.3+

      The following are good sources of info about Oracle:

      1. Koch, George, and Kevin Loney. Oracle 8, The Complete Reference.  Berkeley CA: For Oracle Press by Osborne McGraw-Hill, 1997.  ISBN 0-07-882396-X.
         This book includes introductory database concepts as well as a complete reference to Oracle SQL and PL/SQL statements.  The companion CD contains a complete copy of the book, so you can read it on-line, search it, etc.
      2. Any of the O'Reilly books.  I've been very impressed by all of the O'Reilly books since my early Unix and X-Windows days in the 80's, and they have a complete series on Oracle, covering PL/SQL, the standard packages, etc.

      --Fred

2. MS SQL Server Tips

   1. SQL Tips

      This section contains tips on SQL (Structured Query Language) statements in MS SQL Server.

      1. Dynamic SQL in a Stored Procedure

         Last Updated: 2/7/1999
         Applies to:  MS SQL Server 6.5+

         A typical tradeoff for a database application is dynamic SQL (SQL commands embedded in the application -- for flexibility) vs. stored procedures (pre-compiled SQL procedures stored in the database and invoked by name from the application -- for speed and control over what SQL statements get executed).   However, you can have the best of both worlds by using dynamic SQL inside your stored procedures.  In a stored procedure, you can use the EXEC statement to execute a string of SQL statements that you built dynamically in the stored procedure or read from the database or any other data source.

         Thanks to Steve Rhoads for this tip.

         --Fred

   2. SQL Enterprise Manager Tips

      This section contains tips on the SQL Enterprise Manager tool. It is a graphical front end to the database, allowing you to create, delete, view, and modify all MS SQL Server objects: tables, views, stored procedures, etc.

      1. Keyboard Shortcuts

         Last Updated: 6/20/1999
         Applies to:  MS SQL Server 7.0

         Here is a list of some of the more useful shortcut keys in SQL Enterprise Manager.

         Key	Function
         F1	Help on SQL Enterprise Manager
         Shift-F1	Help on syntax of current SQL statement
         Ctrl-E	Execute selected text in Query Analyzer
         Ctrl-R	Hide/show results pane in Query Analyzer

         Obviously, this list is far from complete.   Please feel free to mail me your favorite shortcuts.  I'll add to this list as time permits.

         See also: Windows Shortcut Keys

         --Fred

      2. SQL Generating SQL

         Last Updated: 2/7/1999
         Applies to:  MS SQL Server 6.5+

         To automate tedious database maintenance chores, you can use SQL statements to generate SQL statements that do your maintenance for you.  For example, to change the permissions on all stored procedures in a database, you can use a SELECT statement like:

         	SELECT 'GRANT EXECUTE ON ' + name + ' TO PUBLIC
                 	GO'
                 	FROM sysobjects
                 	WHERE type = 'P'

         The output of this SELECT statement is a series of alternating GRANT and GO statements, one pair per stored procedures, for all stored procedures in the database.  Then you copy that output as your next set of commands and execute it. 

         Note:  Be sure to leave the line break before the word GO. It is required to start on a new line, after the GRANT statement.

         Thanks to Steve Rhoads for this tip.

         --Fred

   3. See Also

      Last Updated: 6/6/1999
      Applies to:  MS SQL Server 6.5+

      The following are good sources of info about MS SQL Server:

      1. MS SQL Server books on the MSDN Library CD.

      --Fred

3. Differences Between Oracle and MS SQL Server

   1. Concepts and Terminology

      Last Updated: 4/24/2001
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows some differences in concepts and terminology between Oracle and MS SQL Server:

      Concept/Term	Oracle	MS SQL Server
      Database engine	database	database server
      Database (collection of tables)	schema	database
      Roles/Groups	roles	groups
      Database adminstrator account, database owner	dba	sa, dbo
      Data about the database	Data Dictionary - one per server	Database Catalog - one per database "master" database - one per server
      Blocks and extents	blocks and extents	pages and extents
      Network software	SQL*Net	Net-library
      Data stream protocol	Transparent Network Substrate (TNS)	Tabular Data Stream (TDS)
      Case sensitivity of names of tables, columns, etc.	case-insensitive	depends on character sort order, default is case-insensitive
      Synonyms	supported	not supported
      Readonly transaction	supported	not supported

      --Fred

   2. Data Types

      Last Updated: 6/6/1999
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows the corresponding data types in Oracle and MS SQL Server:

      Data Type	Oracle	MS SQL Server
      Fixed Length String	CHAR(n) - limit 2KB	CHAR(n), CHARACTER(n) - limit 255 (6.5) - limit 8KB (7.0)
      Variable Length String	VARCHAR2(n), VARCHAR(n) - limit 4KB in a column - limit 32KB in a variable - VARCHAR is obsolete	VARCHAR(n), CHAR VARYING(n), CHARACTER VARYING(n) - limit 255 (6.5) - limit 8KB (7.0)
      Integer	INTEGER, INTEGER(n), SMALLINT	INTEGER (4 bytes), INT (4 bytes), SMALLINT (2 bytes), TINYINT (1 byte), BIT (1 bit)
      Fixed Point	NUMBER, NUMBER(n), NUMBER(n,d), FLOAT, FLOAT(n), FLOAT(n,d)	NUMERIC, NUMERIC(n), NUMERIC(n,d), DECIMAL, DECIMAL(n), DECIMAL(n,d), DEC, DEC(n), DEC(n,d), MONEY, SMALLMONEY
      Floating Point	DECIMAL	FLOAT, FLOAT(n), DOUBLE PRECISION, REAL,
      Date	DATE	DATETIME, SMALLDATETIME, TIMESTAMP - TIMESTAMP auto-updated
      Binary	RAW(n) - limit 255 bytes	BINARY(n), VARBINARY(n), BINARY VARYING(n) - limit 255 (6.5) - limit 8KB (7.0)
      Large String	LONG, LONG VARCHAR - limit 2GB - limit one per table row CLOB - limit 4GB	TEXT - limit 2GB
      Large Binary	LONG RAW - limit 2GB - limit one per table row BLOB - limit 4GB	IMAGE - limit 2GB
      Multi-byte chars	NCHAR(n) NVARCHAR(n) NCLOB - same limits as CHAR, VARCHAR, CLOB	NCHAR(n), NATIONAL CHAR(n), NATIONAL CHARACTER(n) NVARCHAR(n), NATIONAL CHAR VARYING(n), NATIONAL CHARACTER VARYING(n) NTEXT, NATIONAL TEXT - same limits as CHAR, VARCHAR, TEXT
      OS File	BFILE	<not supported>
      Row Identifier	implicit ROWID column	(use an IDENTITY column)
      Secure OS Label	MLSLABEL, RAW MLSLABEL	<not supported>
      128-bit Unique Number (UUID, GUID)	<not supported>	UNIQUEIDENTIFIER (version 7.0 only)

      --Fred

   3. Limits

      Last Updated: 6/14/2000
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows differences in limits of Oracle and MS SQL Server:

      Description	Oracle	MS SQL Server
      Columns per table	1000	250 (6.5) 1024 (7.0)
      Row size	unlimited	1962 bytes (6.5) 8060 bytes (7.0) - includes pointers, but not data, for TEXT and IMAGE columns
      LONG and LONG RAW columns per row	1 (must be last column)	unlimited (16-byte pointer per)
      LOB, TEXT, and IMAGE columns per row	unlimited (16-byte pointer per)	unlimited (16-byte pointer per)
      Clustered indexes per table	1	1
      Non-clustered indexes per table	unlimited	249
      Columns per index	16	16
      Index row size	2K bytes	900 bytes
      Identifier Length	30 chars	30 chars (6.5) 128 chars (7.0)
      Tables per SELECT	unlimited	16 (6.5) 256 (7.0)
      Source code per stored procedure		64KB (6.5) 250MB (7.0)
      Data type limits	(see Data Types)

      --Fred

   4. Operators

      Last Updated: 6/7/1999
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      Most operators are the same in Oracle and MS SQL Server.  Here are some that differ:

      Description	Oracle	MS SQL Server
      String concatenation	string1 || string2	string1 + string2

      --Fred

   5. Built-In Functions

      Last Updated: 6/7/1999
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      Oracle and MS SQL Server offer many of the same built-in functions.  For example, they both offer ABS, EXP, ROUND, UPPER, LOWER, AVG, COUNT, SUM, ASCII, etc.  The following table shows some of the corresponding functions that don't have the same name. For a more complete list, see "Migrating Oracle Applications to SQL Server"

      Description	Oracle	MS SQL Server
      Smallest integer >= n	CEIL	CEILING
      Modulus	MOD	%
      Truncate number	TRUNC	<none>
      Max or min number or string in list	GREATEST, LEAST	<none>
      Translate NULL to n	NVL	ISNULL
      Return NULL if two values are equal	DECODE	NULLIF
      String concatenation	CONCAT(str1,str2)	str1 + str2
      Convert ASCII to char	CHR	CHAR
      Capitalize first letters of words	INITCAP	<none>
      Find string in string	INSTR	CHARINDEX
      Find pattern in string	INSTR	PATINDEX
      String length	LENGTH	DATALENGTH
      Pad string with blanks	LPAD, RPAD	<none>
      Trim leading or trailing chars other than blanks	LTRIM(str,chars), RTRIM(str,chars)	<none>
      Replace chars in string	REPLACE	STUFF
      Convert number to string	TO_CHAR	STR, CAST
      Convert string to number	TO_NUMBER	CAST
      Get substring from string	SUBSTR	SUBSTRING
      Char for char translation in string	TRANSLATE	<none>
      Date addition	ADD_MONTH or +	DATEADD
      Date subtraction	MONTHS_BETWEEN or -	DATEDIFF
      Last day of month	LAST_DAY	<none>
      Time zone conversion	NEW_TIME	<none>
      Next specified weekday after date	NEXT_DAY	<none>
      Convert date to string	TO_CHAR	DATENAME, CONVERT
      Convert string to date	TO_DATE	CAST
      Convert date to number	TO_NUMBER(TO_CHAR(d))	DATEPART
      Date round	ROUND	CONVERT
      Date truncate	TRUNC	CONVERT
      Current date	SYSDATE	GETDATE
      Convert hex to binary	HEXTORAW	CAST
      Convert binary to hex	RAWTOHEX	CONVERT
      If statement in an expression	DECODE	CASE ... WHEN or COALESCE
      User's login id number or name	UID, USER	SUSER_ID, SUSER_NAME
      User's database id number or name	UID, USER	USER_ID, USER_NAME
      Current user	USER	USER

      --Fred

   6. Differences in SQL Syntax

      Last Updated: 3/21/2001
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows the different syntax used in Oracle and MS SQL Server for the same SQL operations:

      Description	Oracle	MS SQL Server
      Left Outer Join	WHERE column1 = column2(+)	FROM table1 LEFT OUTER JOIN table2 ON table1.column1 = table2.column2 Note:  The following syntax is also supported, but is no longer recommended: WHERE column1 *= column2
      Right Outer Join	WHERE column1(+) = column2	FROM table1 RIGHT OUTER JOIN table2 ON table1.column1 = table2.column2 Note:  The following syntax is also supported, but is no longer recommended: WHERE column1 =* column2
      Full Outer Join		FROM table1 FULL OUTER JOIN table2 ON table1.column1 = table2.column2
      SELECT without FROM	SELECT 'hello world' FROM DUAL	SELECT 'hello world'
      SELECT data into a table	CREATE TABLE AS SELECT ...	SELECT ... INTO
      Intersection of 2 SELECTS	SELECT ... INTERSECT SELECT ...	SELECT ... WHERE EXISTS (SELECT ...)
      Subtraction of 2 SELECTS	SELECT ... MINUS SELECT ...	SELECT ... WHERE NOT EXISTS (SELECT ...)
      INSERT into a JOIN	INSERT INTO SELECT ...	Create a VIEW and INSERT INTO it.
      UPDATE data in a JOIN	UPDATE SELECT...	Create a VIEW and INSERT INTO it.
      UPDATE one table based on criteria in another table	<not supported>	UPDATE table FROM ...
      DELETE rows from one table based on criteria in another table	<not supported>	DELETE FROM table FROM ...
      DROP a column from a table	<not supported until Oracle 8i>	ALTER TABLE table_name DROP COLUMN column_name
      Readonly VIEW	CREATE VIEW ... WITH READONLY	GRANT SELECT ...
      Save point	SAVEPOINT	SAVE TRANSACTION
      Table lock	LOCK TABLE...IN SHARE MODE	SELECT...table_name (TABLOCK)
      Exclusive table lock	LOCK TABLE...IN EXCLUSIVE MODE	SELECT...table_name (TABLOCKX)
      Reserving index space	PCTFREE=0	FILLFACTOR=100
      Declaring a local variable	DECLARE varname type;	DECLARE @varname type
      Initializing a local variable	DECLARE varname type := value;	<not supported>
      Declaring a constant	DECLARE varname CONSTANT type := value;	<not supported>
      Assigning to a variable	varname := value SELECT value INTO varname	SET @varname = value SELECT @varname = value
      Assigning to a variable from a cursor	FETCH cursorname INTO varname	FETCH NEXT FROM cursorname INTO varname
      Declaring a cursor	CURSOR curname (params) IS SELECT ...;	DECLARE curname CURSOR FOR SELECT ...
      If statement	IF ... THEN ELSIF ... THEN ELSE ENDIF	IF ... BEGIN ... END ELSE BEGIN ... END
      While loop	WHILE ... LOOP END LOOP	WHILE ... BEGIN ... END
      Other loops	FOR ... END LOOP LOOP ... END LOOP	<not supported>
      Loop exit	EXIT, EXIT WHEN	BREAK, CONTINUE
      Print output	DBMS_OUTPUT.PUT_LINE	PRINT
      Raise error	RAISE_APPLICATION_ERROR	RAISERROR
      Statement terminator	Semi-colon (;)	<none required>

      Thanks to Tom Johnston for catching a mistake in this tip. I had the FROM DUAL in the wrong column.

      --Fred

   7. Differences in SQL Semantics

      Last Updated: 6/6/1999
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows some semantic differences between Oracle and MS SQL Server:

      Description	Oracle	MS SQL Server
      Commit	Explicit COMMIT statement required	Automatic commit unless SET IMPLICIT_TRANSACTIONS ON
      Reading uncommitted data	Database does temporary internal  rollback to reconstruct most recently committed data for reader.	Depending on options, reader as allowed to read uncommitted data, or is forced to wait for writer to commit or rollback.
      Releasing cursor data	CLOSE CURSOR releases all data.  You can't re-open.	CLOSE CURSOR does not release data.  You must explicitly call DEALLOCATE CURSOR.  Until then, you can re-open the cursor.
      Implicit data conversion in a statement like the following where vc is a column of type VARCHAR2: SELECT * FROM person WHERE vc =123	As each row is fetched from the table, an attempt is made to convert it to a number for the comparison with 123.  If any row contains a value that cannot be converted to a number, a runtime error occurs.	The number 123 is converted to the string '123' once, and then the data is fetched from the table.  If any row contains a value that cannot be converted to a number, it simply doesn't match '123' and is skipped without any error.
      Conversion to NULL	Setting a VARCHAR2 column to ' (the empty string) makes it NULL.	Setting a VARCHAR column to ' makes it the empty string (not NULL).

      --Fred

   8. Differences in Managing Databases

      Last Updated: 6/6/1999
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows some differences in how databases are managed in Oracle and MS SQL Server:

      Description	Oracle	MS SQL Server
      Model database	No model database	Newly created databases inherit characteristics (users, etc.) from the special database named "model".

      --Fred

   9. Differences in Managing Database Objects

      Last Updated: 6/6/1999
      Applies to:  Oracle 7.3+, MS SQL Server 6.5+

      The following table shows some differences in how database objects (tables, views, stored procedures, etc.) are managed in Oracle and MS SQL Server:

      Description	Oracle	MS SQL Server
      Fully qualified name	[schema.]table [schema.]view	[[[server.][database].][owner].]table [[[server.][database].][owner].]view
      Temp tables	Pre 8i:  Temporary tables must be deleted explicitly 8i+:  CREATE GLOBAL TEMPORARY TABLE	#table -- Any table named starting with a pound sign (#) is automatically deleted when the user logs off or the procedure ends. ##table -- Same as above, except that the table is accessible to other users.
      Re-creating an object	CREATE OR REPLACE ...	DROP ... CREATE ...
      Create view before dependent tables	CREATE FORCE VIEW	Not supported.  Tables used by view must exist before view can be created.

      --Fred

   10. Differences in Managing Users

       Last Updated: 6/6/1999
       Applies to:  Oracle 7.3+, MS SQL Server 6.5+

       The following table shows some differences in how users are managed in Oracle and MS SQL Server:

       Description	Oracle	MS SQL Server
       Membership in groups	Each user can be a member of any number of groups.	Each user can be a member of only one group other than "public".

       --Fred

   11. Differences in Integration with MS ADO, RDO, etc.

       Last Updated: 6/6/1999
       Applies to:  Oracle 7.3+, MS SQL Server 6.5+

       The following table shows the different techniques used in Oracle and MS SQL Server to interact with MS ADO, RDO, etc.:

       Description	Oracle	MS SQL Server
       Return a recordset to the caller	Return a handle to a cursor. For more info:  See MS KB article Q174679.	SELECT with no INTO clause; Multiple such SELECTs return multiple recordsets

       --Fred

   12. Miscellaneous Differences

       Last Updated: 6/6/1999
       Applies to:  Oracle 7.3+, MS SQL Server 6.5+

       The following table shows miscellaneous differences between Oracle and MS SQL Server:

       Description	Oracle	MS SQL Server
       Generate unique numbers	CREATE SEQUENCE	IDENTITY column of a table
       Cascaded DELETE	DELETE CASCADE ...	(use triggers)
       Call a user-defined function from a SQL statement (as column of SELECT or expression in WHERE clause)	supported	not supported

       --Fred

   13. See Also

       Last Updated: 3/3/2001
       Applies to:  Oracle 7.3+, MS SQL Server 6.5+

       The following are good sources of info about differences between Oracle and MS SQL Server:

       1. Bowman, Judith S., Sandra L. Emerson, and Marcy Darnovsky. The Practical SQL Handbook. Addison-Wesley Publishing Company, 1993.  ISBN 0-201-62623-3.
          This book gives a good introduction to SQL, with a slight emphasis on Sybase, but with a useful summary in the back of the syntax for each of the SQL statements (SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, GRANT, REVOKE, etc.) for each of the major databases (Oracle, Sybase, DB2, Informix, Ingres, etc.)  The book pre-dates MS SQL Server, but the Sybase info is a good approximation since MS SQL Server is a derivative of Sybase.
          
       2. "Migrating Oracle Applications to SQL Server" on MSDN CD, and at MS TechNet Web site:
          http://www.microsoft.com/TechNet/sql/Tools/Sqldevkt/ORCL2SQL.asp
          Microsoft clearly intended this to be used in one direction only, but I've used it quite successfully to translate my SQL Server knowledge to Oracle as well.