Comparing Oracle and SQL Server Code – Part 1

Problem

In this tip we are going to compare the SQL Server (T-SQL) and Oracle (PL-SQL) extensions of the SQL language. The tip will compare both T-SQL and PL-SQL languages with respect to retrieving data, creating databases, tables, variables, etc.

Solution

This tip will compare the code between SQL Server and Oracle for the following:

  • Database Creation
  • Changing database usage
  • List databases
  • Table creation
  • Data insertion
  • Create Referential Integrity
  • Create auto incrementing values
  • Capture and format the date
  • Capture the variance
  • Determine the position of a word
  • Generate random numbers
  • Assign a value to a variable
  • List of tables and views in a database

Database Creation in SQL Server vs. Oracle

SQL ServerOracle
CREATE DATABASE [DB2]
CONTAINMENT = NONE
ON PRIMARY
( NAME = N’DB2′, FILENAME = N’C:\SQL\db2.mdf’ , SIZE = 3072KB , MAXSIZE = UNLIMITED, FILEGROWTH = 1024KB )
LOG ON
( NAME = N’ssis_log’, FILENAME = N’C:\sql\db2_log.ldf’ , SIZE = 1024KB , MAXSIZE = 2048GB , FILEGROWTH = 10%)
GO

ALTER DATABASE [db2] SET COMPATIBILITY_LEVEL = 120
GO

ALTER DATABASE [db2] SET RECOVERY FULL
GO

ALTER DATABASE [DB2] SET FILESTREAM( NON_TRANSACTED_ACCESS = OFF )
GO

The example creates a data file named db2.mdf which stores the data. The log file is stored in the db2_log.ldf the maximum size for the data file is unlimited and the log file can have a maximum size of 2048 GB. The compatibility level is used for backward compatibility with earlier SQL Server versions. The recovery model is used to set the mode to recover information using the transaction log files. Finally, the filestream option is used to store unstructured data.

In Oracle, creating a database is a more complex process. In order to see the steps, refer to this link: Creating a Database with the CREATE DATABASE Statement.

Change Databases in SQL Server vs. Oracle

SQL ServerOracle
USE DB2
GO		In Oracle a Database is a complete instance. You cannot switch contexts with a USE command.

List of Databases in SQL Server vs. Oracle

SQL ServerOracle
exec sp_databases
GO		In UNIX, Linux you can use the ps command to see the list of processes and find the ones related to Oracle. In Windows, query the following registry key: HKEY_LOCAL_MACHINE\ SOFTWARE\ORACLE\oracle_home and check the ORA_SID related parameters

Table Creation in SQL Server vs. Oracle

SQL ServerOracle
CREATE TABLE customer
(
id INT NOT NULL ,
NAME VARCHAR(30) NULL ,
GENDER CHAR(1) NULL ,
BIRTH_DT DATE NULL ,
LASTNAME VARCHAR(30) NULL ,
CITY VARCHAR(30) DEFAULT ‘NY’
CONSTRAINT PK_PERSON PRIMARY KEY (id)
)
GO

In this example, the primary key is the id which does not accept nulls, the other columns accept null values. By default the city is NY. For more information about creating tables and about SQL Server data types, refer to these links:

CREATE TABLE customer
(
id INT NOT NULL ,
NAME VARCHAR(30) NULL ,
GENDER CHAR(1) NULL ,
BIRTH_DATE DATE NULL ,
LASTNAME VARCHAR2(30) NULL ,
CITY VARCHAR2(30) DEFAULT ‘NY’
CONSTRAINT PK_PERSON PRIMARY KEY (id)
)
/

As you can see, Oracle and SQL Server are very similar, but in some cases the data types can differ. For more information about creating tables and about Oracle data types, refer to these links:

Insert data in a table in SQL Server vs. Oracle

SQL ServerOracle
insert into dbo.customer
values (5,’John’,’m’,’10-21-1980′,NULL,default)
go

Default is used to insert the value by default defined when creating a table. You can assign null values to columns if they accept null values. Check out the SQL Server INSERT Tutorial.

insert into customer values(5,’John’,’m’,to_date(’10/21/1980′,’mm/dd/yyyy’), NULL,default);

The main difference between SQL Server and Oracle is that in Oracle you have to use the function to_date and specify the date format to insert the information.

Foreign keys in SQL Server vs. Oracle

SQL ServerOracle
CREATE TABLE products_sold
(
product_id numeric(10) not null,
customer_id INT not null,
CONSTRAINT fk_pr
FOREIGN KEY (customer_id)
REFERENCES customer(id) )
GO

The syntax for foreign keys is the same in Oracle and SQL Server. Learn more about Foreign Keys.

CREATE TABLE products_sold
(
product_id numeric(10) not null,
customer_id INT not null,
CONSTRAINT fk_pr
FOREIGN KEY (customer_id)
REFERENCES customer(id) );

Autonumeric values in SQL Server vs. Oracle

SQL ServerOracle
An identity is used to creates auto-generated values for rows. In this case (IDENTITY(1,1)) the value starts in 1 and the incremental value is 1.

CREATE TABLE CUSTOMER2
(id_num int IDENTITY(1,1),
NAME VARCHAR(30) NULL ,
GENDER CHAR(1) NULL ,
BIRTH_DT DATE NULL ,
LASTNAME VARCHAR(30) NULL ,
CITY VARCHAR(30) DEFAULT ‘NY’
CONSTRAINT PK_PERSON PRIMARY KEY (id)
)
GO

You can also use sequences in SQL Server like in Oracle. For more information, check out this resource on sequence numbers.

In Oracle there was not an auto increment option like in SQL Server until Oracle 12c.

You can use sequences that are similar than in SQL Server (they existed before than the SQL Server sequences). The following example shows a sequence from 1 to 1000.

CREATE SEQUENCE myseq
MINVALUE 1
MAXVALUE 1000
START WITH 1
INCREMENT BY 1
CACHE 20;

In order to insert a sequence use this example:

insert into customer values(myseq.nextval)

In Oracle 12c, you can use the identity option:

CREATE TABLE product (id NUMBER GENERATED ALWAYS AS IDENTITY, prod_name VARCHAR2(30) );

Current date in SQL Server vs. Oracle

SQL ServerOracle
select CONVERT (date, GETDATE())
go

Learn more about SQL Server Dates.

SELECT TO_CHAR (SYSDATE, ‘MM-DD-YY’) “NOW” FROM DUAL;

Modify the date format in SQL Server vs. Oracle

SQL ServerOracle
select FORMAT (getdate(), ‘MM-dd-yyyy’) as date
GO

For more information, refer to this link.

SELECT TO_CHAR (SYSDATE, ‘MM-DD-YYYY’) “DATE” FROM DUAL;

For more information, refer to this link: http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions172.htm

Variance of a value in SQL Server vs. Oracle

SQL ServerOracle
select var(id) from customer
go		select variance(id) from customer;

or

select var(id) from customer;

Find the position within a string in SQL Server vs. Oracle

SQL ServerOracle
SELECT CHARINDEX( ‘Gates’, ‘Bill Gates’, 1);

This example shows the position of the word Gates in Bill Gates.

SELECT INSTR(‘Bill Gates’, ‘Gates’, 1) FROM dual;

In Oracle you also have INSTR2 (UCS2 code points), INSTR4 (UCS2 code points), INTRB (bytes), INSTRC (UNICODE) functions.

Generate random numbers in SQL Server vs. Oracle

SQL ServerOracle
SELECT ROUND(RAND()*6,0)
GO		select trunc(dbms_random.value(1,6)) from dual;

Assign a value to a variable and show the results in SQL Server vs. Oracle

SQL ServerOracle
declare @var int=1
select @var
go		VARIABLE var NUMBER BEGIN :varl:=1; END; / PRINT var;

Tables in the current database in SQL Server vs. Oracle

SQL ServerOracle
SELECT table_name FROM information_schema.tables
go		select table_name from user_tables;

Views in the current database in SQL Server vs. Oracle

SQL ServerOracle
SELECT * FROM information_schema.views
go		SELECT View_name from user_views;

Next Steps

For more information, refer to the following links:

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