Mssql to oracle

SQL Server to Oracle
Frank Shen-申建忠

主要差異點
• 資料庫結構
• 預存程式(Stored Procedure)開發語言
• 交易控制(Transaction Control)

資料庫結構-名詞比較
Oracle MS SQL Server
Database Database
Schema Database and database owner(DBO)
Tablespace Database
User User
Role Group/Role
Table Table
Temporary Table Temporary Table
Cluster N/A
Column-level check constraint Column-level check constraint
Column default Column default
Unique key Unique key or identity property for a column
Primary key Primary key

資料庫結構-名詞比較(Cont.)
Foreign key Foreign key
Index Non-unique index
PL/SQL Procedure T-SQL stored procedure
PL/SQL Function T-SQL stored Function
Package N/A
AFTER trigger Trigger
BEFORE trigger Complex rule
Trigger for each row N/A
Synonym N/A
Sequence Identity property for a column
Snapshot N/A
View View

資料庫伺服器架構比較
Oracle
Database
Instance
tablespace
table
SQL Server
database
table
Instance

Instance Instance
Database
Instance
Database Database

Table
Table
Schema
Database
Server
Schema
Database
Server
Schema
Schema
Database

實例結構比較
SGA
background processes
*nix : process based
windows : thread based
Memory pool
threads

Program,Process,Thread
• Program
• 一群程式碼的集合，用以解決特定的問題。
• Process
• 由Program所產生的執行個體，一個Program同時被執行多次，將產生
多個process。
• Process由Memory Space與至少一個Thread組成。
• Thread
• 代表從某個起始點開始，到目前為止所有函數的呼叫路徑，以及這些呼
叫路徑上所用到的區域變數。程式的執行狀態以及CPU內部的暫存器資
訊將記錄在記憶體。
• Thread由Stack與目前CPU狀態組成

共用記憶體結構比較
SGA Memory pool
Buffer Cache Shared Pool
Log Buffer Large Pool
Java Pool
Streams
pool
Fixed
SGA
Buffer Cache
Columnstore
Cache
Log Cache
Procedure
Cache
System
Structures
Connection
Context
CLR
Hosting
Layer

背景程序(background process)比較
Oracle process Oracle Identifier SQL Server equivalent Required
Process Monitor PMON SQLOS Yes
System Monitor SMON Database
Cleanup/Shrinking
Yes
Database Writers DBWn Lazywriter Yes
Checkpoint Process CKPT Database Checkpoint Yes
Log Writer LGWR Log Writer Yes
Recover Process RECO MS DTC No
Archiver Processes ARCn N/A N/A
Job Queue Processes Jnnn SQL Agent No
Job Queue Coordinators CJQn SQL Agent No
Queue Monitor Processes QMNn SQL Agent NO
Parallel Query Slaves Pnnn Worker Threads Yes
Dispatchers Dnnn Networker Thread Yes
Shared Servers Snnn Worker Threads Yes

資料庫檔案結構比較
OS: Windows Server 2012 R2 Oracle 12c SQL Server 2014
data block size(Min:Max) 2 KB ~ 16 KB(Linux/Windows)
32 KB(other OSs)
8 KB ~ 8 KB
Maximum file size Smallfile : 4百萬blocks
Bigfile : 40億blocks
16 TB
Maximum number of files 65533 32767
Maximum database size 4 EB(16 KB blocksize/Bigfile) 524 PB
Maximum controlfile size 201031680 logical blocks N/A
Instance per host unlimited 50 for all editions of SQL Server
Maximum database extents 4 GB 64K
Maximum number of tablespaces 65536 32767(filegroups)
Maximum logfile size 2 GB 2 TB

資料庫實體檔案結構
Data File Data FilePhysical
Logical
Segment
Extent
B
l
o
c
k
B
l
o
c
k
B
l
o
c
k
Segment
Segment
TablespaceTablespace
Heap/Index
Extent
P
a
g
a
P
a
g
e
P
a
g
e
Heap/Index
Heap/Index
FilegroupFilegroup

Segment,Extent,Block(Page)
結構 Oracle SQL Server
最小I/O單位 Block Page
Block Size 2 KB ~ 32 KB 8 KB
最小配置單位 Extent Extent
Extent Size Varible 64 KB
Segment 所有需要空間的邏輯結構 Heap/Index

Tablespace與Filegroup的比較
System tablespace
Sysaux tablespace
Temporary tablespace
Undo tablesapce
User1 Data tablespace
User1 Index tablespace
User2 Data/Iindex
tablesapce
Redo
Log
Redo
Log
Redo
Log
Master DB
Resource DB
Model DB
MSDB
Temp DB
TABLE
INDEX
Log
File
Log
File
User Database
User2 Database

開發語言
• SQL(Structured Query Language)
• 支援ANSI-SQL 2016 (12c R2)

DML
DDL
DCL
TCL
SELECT … INTO
INSERT
UPDATE
DELETE
MERGE
CREATE
ALTER
DROP
TRUNCATE
GRANT
REVOKE
COMMIT
ROLLBACK
SAVEPOINT
SQL Statement

DDL(Data Definition Language)
• CREATE,ALTER,DROP,TRUNCATE(table only)
• Identifier名字長度
• 少於30 characters(MS SQL Server可達128 characters)
• 英文字母,數字,特殊符號(_,#,$)組成
• 如果沒有使用雙引號，則不能使用數字開頭或Oracle保留字

Table種類的比較
Heap-organized table Heap
Clustered table Indexed view
Index-organized table Clustered index
Partition table Partitioned table
Temporary table Temporary table
External table Linked server
Object type Table type
Table with inmemory option In-Memory OLTP table
Hybrid columnar compressed table Columnstore clustered index

Constraint種類的比較
NOT NULL NOT NULL
Unique Unique
Primary key Primary key
Foreign key Foreign key
Check Check

Index種類比較
種類 Oracle MS SQL Server
B-tree Yes Yes
B-tree composite Yes(32 columns) Yes(16 columns)
B-tree cluster Yes Yes
B-tree reverse key Yes No
B-tree key compressed Yes No
B-tree function-based Yes No
B-tree index organized table Yes Yes(Clustered)
B-tree partitioned Yes No
Bitmap Yes No
Bitmap join Yes No
Invisible index Yes No

View種類的比較
種類 Oracle MS SQL Server
Simple Yes Yes
Join Yes Yes
Partitioned Yes Yes
Updateable Yes Yes
Inline Yes Yes
Indexed Yes Yes

資料型態的比較-數值
Number(19,0) BigInt
Int/Number(10,0) Int
Smallint/Number(5,0) SmallInt
Number(3,0) TinyInt
Decimal(p,s)/Number(p,s) Decimal(p,s)
Number(p,s) Numeric(p,s)
Float Float
Number(1) Bit
Number(19,4) Money
Number(10,4) SmallMoney

資料型態的比較-文字
Data type Size(Bytes) Data type Number of chars Size(Bytes)
Char 1~2000 Char 1~8000 1~8000
Nchar 1~2000 Nchar 1~4000 2~8000
Varchar 1~4000 Varchar
Varchar(max)
1~8000
1~231-1
0~8000
0~2 GB
NVarchar 1~4000 Nvarchar
Nvarchar(max)
1~8000
1~230-1
0~4000
0~2 GB
Varchar2 1~32767
1~4000(<12c)
Long 1~231 Text/Varchar(max) 1~231-1 0~2 GB
CLOB 1~232 * block
NCLOB 1~232 * block

資料型態的比較-日期
Data type Value Data type Value
Date Year,Month,Day,
Hour,Minute,Second
Date Year,Month,Day
SmallDateTime Year,Month,Day,
Hour,Minute,Second
(精確度:minute)
DateTime Year,Month,Day,
Hour,Minute,Second,fract
ional second(3)
(精確度:fractional
second)
Timestamp Year,Month,Day,
ional second(9)
DateTime2 Year,Month,Day,
ional second(7)
(精確度:fractional
second)

資料型態的比較-日期(Cont.)
Data type Values Data type Values
Timestamp with time
zone
Year,Month,Day,
ional second,time zone
hour,time zone minute
DateTimeOffset Year,Month,Day,
Timestamp with local
time zone
Year,Month,Day,

資料型態的比較-Binary
BLOB Image/Varbinary(max)
Raw image/Varbinary(max)
Long Raw Image/Varbinary(max)
BFile Varbinary(max) Filestream

Date Range
• Oracle
• January 1,4712 BC ~ December 31,9999 AD
• MS SQL Server
• January 1,1 AD ~ December 31,9999 AD (Date)
• January 1,1753 AD ~ December 31,9999 AD (Datetime)
• January 1,1 AD ~ December 31,9999 AD (DateTime2)
• January 1,1 AD ~ December 31,9999 AD (DateTimeOffset)
• January 1,1900 AD ~June 6,2079 AD (SmallDateTime)

SELECT指令的差異-1
• SELECT list column alias
• Oracle : SELECT ename last_name FROM emp;
• MS SQL Server : SELECT last_name=ename FROM emp;
• SELECT INTO
• Oracle : INSERT INTO t2 SELECT col1,col2 FROM t1;
• MS SQL Server : SELECT col1,col2 INTO t2 FROM t1;
• SELECT list字串相連
• Oracle : SELECT ‘A’|| ‘B’ FROM dual;
• MS SQL Server : SELECT ‘A’+ ‘B’;

• SELECT list呼叫函數
• Oracle : SELECT upper(‘abc’) FROM dual;
• MS SQL Server : SELECT upper(‘abc’);
• 被呼叫函數沒有輸入參數
• Oracle : SELECT func1 FROM dual;
• MS SQL Server : SELECT func1();

• IN list數量
• Oracle : IN (x1,x2,…,x1000)最多可以有1000個值
• MS SQL Server : (x1,x2,...,xN)沒有限制數量
• TOP-N
• Oracle :
• SELET … FROM .. ORDER BY … FETCH NEXT 10 ROWS ONLY;
• MS SQL Server
• SELECT TOP 10 … FROM ORDER BY;

SELECT
FROM
WHERE
ORDER BY
FETCH
t1
c1|c2|c3 |c4|c5
c1,c3,c5
c2=10
c2
c1|c3|c5
Result
FIRST 1 ROWS ONLY

SET operator的比較
SET Operator Oracle MS SQL Server
聯集ALL UNION ALL UNION ALL
聯集 UNION UNION
交集 INTERSECT INTERSECT
差集 MINUS EXCEPT

Bit Operator
Operator Oracle MS SQL Server
bit and bitand(6,3)
utl_raw.bit_and(hextoraw(6),hexto
raw(3))
6&3
bit or 6+3-bitand(6,3)
utl_raw.bit_or(hextoraw(6),hextora
w(3))
6|3
bit exclusive or (6+3)-bitand(6,3)2
utl_raw.bit_xor(hextoraw(6),hextor
aw(3))
6^3
bit not utl_raw.bit_complement(hextoraw(
6))
~6

DML(Data Manipulation Language)
• SELECT,INSERT,UPDATE,DELETE,MERGE
• LOCK Type
• SELECT
• MS SQL Server : Shared locks(S)
• 在讀取資料的過程中，被讀的資料被加上此種Lock，直到讀取完成後釋放。
• 因此在讀取過程中，其他交易(UPDATE/DELETE)暫時無法異動這些資料，除非
isolation level設定為read uncommitted或read committed snapshot。
• Oracle : 沒有加上任何LOCK
• 除非使用SELECT … FOR UPDATE，將對所讀取的rows加上exclusive lock。

INSERT指令的差異
• INSERT [INTO] t1
• Oracle : INTO是必要關鍵字，一定要出現。
• MS SQL Server : INTO是選項。

UPDATE指令的差異
• MS SQL Server
• UPDATE t1
SET col1 = t2.col1
FROM t1,t2
WHERE t1.col2=t2.col2 AND t1.col3=10;
• Oracle
• MERGE INTO t1
USING t2 ON (t1.col2=t2.col2)
WHEN MATCHED
THEN UPDATE SET col1=t2.col1 WHERE col3=10;

DELETE指令的差異
• MS SQL Server
• DELETE
FROM t1
FROM t1,t2
WHERE t1.col1=t2.col1 AND t1.col3=10;
• Oracle
• DELETE
• FROM t1
• WHERE rowid IN (SELECT t1.rowid FROM t1,t2 WHERE
t1.col1=t2.col1 AND t1.col3=10);

交易控制指令的比較
COMMIT COMMIT TRANSACTION
ROLLBACK ROLLBACK TRANSACTION
SAVEPOINT SAVE TRANSACTION
SET TRANSACTION SET

交易控制的差異
• MS SQL Server必須明確要求，才能將多個DMLs組成一個交易。
• USE db1;
GO
SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
GO
BEGIN TRANSACTION;
GO
UPDATE …;
GO
DELETE …;
GO
COMMIT TRANSACTION;
GO
• 當一個DML操作結束後，MS SQL Server自動COMMIT該交易。

交易控制的差異
• Oracle自動將多個DMLs組成一個交易。
• UPDATE …;
DELETE …;
COMMIT;
• 如果沒有明確結束交易(COMMIT/ROLLBACK)，則此DMLs交易
將持續繼續。

Transaction
DMLs
(1,多個)
DDL
(1個)
DCL
(1個)
SELECT
INSERT
UPDATE
DELETE
MERGE
CREATE
ALTER
DROP
TRUNCATE(TABLE only)
TABLE/INDEX/VIEW…
GRANT
REVOKE

Transaction開始:上個交易結束後,所遇到第一個DML(除SELECT)時,自動開始.
Transaction結束:
COMMIT(確認)
ROLLBACK(倒回)
明確使用COMMIT
自動認定COMMIT
執行DDL
執行DCL
正常結束連線
明確使用ROLLBACK
自動認定ROLLBACK
不正常結束連線
Server崩潰
SQL> COMMIT;
SQL> ROLLBACK;

Isolation level的比較
Isolation level Dirty read Non-repeatable
read
Phantom read Oracle MS SQL
Server
Read uncommitted Yes Yes Yes No Yes
Read committed No Yes Yes Yes Yes
Repeatable read No No Yes No Yes
Serializable No No No Yes Yes

Lock level的比較
• Lock escalation
• Oracle : 不會
• MS SQL Server : 會
• Lock Level
• Oracle :
• Table Level
• Row Level
• MS SQL Server :
• Table Level
• Partition Level
• Page Level
• Row Level

階段作業控制指令的比較
ALTER SESSION SET
SET ROLE sp_setapprole
ALTER SYSTEM set_configure
ALTER DATABASE set_dboption

預存程式開發語言
• Oracle
• PL/SQL(Procedure Language/SQL)
• MS SQL Server
• T-SQL(Transact SQL)

Stored Program種類比較
PL/SQL Procedure T-SQL stored procedure
PL/SQL Function T-SQL stored Function
Package N/A
After Statement Trigger Trigger

Program Unit
Standalone Procedure
Do something
Standalone Function
Do something and return one value
Package
Trigger
procedure
function

DECLARE
BEGIN
EXCEPTION
END
變數宣告
程式邏輯
例外處理
例外
變數
block structure
必要
選項

DML
DDL
DCL
TCL
SELECT … INTO
INSERT
UPDATE
DELETE
MERGE
CREATE
ALTER
DROP
TRUNCATE
GRANT
REVOKE
COMMIT
ROLLBACK
SAVEPOINT
SQL Statement
EXECUTE IMMEDIATE ‘DDL/DCL’;
Data Manipulation Language
Data Definition Language
Data Control Language
Transaction Control Language

SubProgram’s
Parameters notation
Passing mode
type
Formal
Actual
Positional
Named
IN OUT
IN
OUT
Mixed
Call By Value
Call By Reference
CREATE PROCEDURE proc1(p1 NUMBER,p2 NUMBER)
proc1(100,1);
proc1(100,1);
proc1(p2=>1,p1=>100);
proc1(100,p2=>1);

呼叫procedure方法的比較
• Oracle
• EXEC proc1(10,20) - Positional
• EXEC proc1(p2 => 20,p1 => 10) - Named
• MS SQL Server
• SET @p1 = 10
• SET @p2 = 20
• EXEC proc1 @p1,@p2 - Positional
• EXEC proc1 @p2=20,@p1=10 - Named

SQL> CREATE OR REPLACE PROCEDURE proc1(p_id IN NUMBER,p_sal OUT NUMBER)
2 IS
3 v_last_name employees.last_name%TYPE;
4 BEGIN
5 SELECT last_name,salary INTO v_last_name,p_sal
6 FROM employees
7 WHERE employee_id=p_id;
8 dbms_output.put_line(v_last_name||':'||p_sal);
9 END;
10 /
SQL> DECLARE
2 v_sal NUMBER;
3 BEGIN
4 proc1(200,v_sal);
5 dbms_output.put_line(v_sal);
6 END;
7 /
Whalen:4400
4400

SQL> DECLARE
2 v_sal NUMBER;
3 BEGIN
4 proc1(200,v_sal);
6 END;
7 /
SQL> DECLARE
2 v_sal NUMBER;
3 BEGIN
4 proc1(p_sal=>v_sal,p_id=>200);
6 END;
7 /

SQL> CREATE OR REPLACE FUNCTION func1(p_id NUMBER) RETURN VARCHAR2
2 IS
4 BEGIN
5 SELECT last_name INTO v_last_name
6 FROM employees
8 RETURN v_last_name;
9 dbms_output.put_line(v_last_name);
10 END;
11 /
SQL> BEGIN
2 dbms_output.put_line(func1(100));
3 END;
4 /
King
已順利完成 PL/SQL 程序.

SQL> CREATE OR REPLACE FUNCTION func2(p_id NUMBER,p_fname OUT VARCHAR2)
2 RETURN VARCHAR2
3 IS
5 BEGIN
6 SELECT last_name,first_name INTO v_last_name,p_fname
7 FROM employees
9 RETURN v_last_name;
10 dbms_output.put_line(v_last_name);
11 END;
12 /
SQL> DECLARE
2 v1 VARCHAR2(30)
3 BEGIN
4 dbms_output.put_line(func2(100,v1));
5 dbms_output.put_line(v1);
6 END;
7 /
King
Steven
已順利完成 PL/SQL 程序.

Trigger events的比較
Type Oracle MS SQL Server
Before Statement Yes No
Before Row Yes No
After Row Yes No
After Statement Yes Yes

Table
DDL
Schema
Database
DML
View
Database Operation
BEFORE
AFTER
INSTEAD OF
Timing
Event
INSERT
UPDATE
DELETE
Level
Statement
Row
Define on
Type
Trigger
STARTUP
SHUTDOWN
LOGON
LOGOFF
ServerError

SQL> SELECT * FROM t1;
COL1 COL2
---------- ----------
1 10
2 20
3 30
4 40
SQL> UPDATE t1 SET col2=col2+10 WHERE col1 = 4;
Before Statement Trigger
Before Row Trigger
After Row Trigger
After Statement Trigger
已更新 1 個資料列.

COL1 COL2
---------- ----------
1 10
2 20
3 30
4 50
SQL> UPDATE t1 SET col2=col2+10 WHERE col1 IN (3,4);
Before Row Trigger
After Row Trigger
Before Row Trigger
After Row Trigger
After Statement Trigger
已更新 2 個資料列.

COL1 COL2
---------- ----------
1 10
2 20
3 30
4 40
SQL> UPDATE t1 SET col2=col2+10 WHERE col1 IN (1,2);
Before Row Trigger
After Row Trigger
Before Row Trigger
After Row Trigger
UPDATE t1 SET col2=col2+10 WHERE col1 IN (1,2)
*
ERROR 在行 1:
ORA-00001: 違反必須為唯一的限制條件 (HR.SYS_C0010215)

UPDATE t1
SET col2=col2+10
WHERE col1 = 1
1
2
3
4
20
20
30
40
col1
col2
BEFORE STATEMENT
AFTER STATEMENT
BEFORE ROW
AFTER ROW
Constraint check
1.
2.
3. 5.
4.
6.
:OLD.col1=1
:OLD.col2=10
:NEW.col1=1
:NEW.col2=20
1 10
2 20
3 30
4 40
實驗結果-1

UPDATE t1
SET col2=col2+10
WHERE col1 IN (1,3)
1
2
3
4
20
20
40
40
col1
col2
BEFORE STATEMENT
AFTER STATEMENT
BEFORE ROW
BEFORE ROW
AFTER ROW
AFTER ROW
Constraint check
Constraint check
1.
2.
3. 8.
4.
5.
6. 8.
7.
9.
:OLD.col1=1
:OLD.col2=10
:NEW.col1=1
:NEW.col2=20
:OLD.col1=3
:OLD.col2=30
:NEW.col1=3
:NEW.col2=40
1 10
2 20
3 30
4 40
實驗結果-2
Primary Key/Unique/FK

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