Microsoft T-SQL to Oracle SQL translation

Question

I\'ve worked with T-SQL for years but I\'ve just moved to an organisation that is going to require writing some Oracle stuff, probably just simple CRUD operations at least u

Answer 1

I have done a few SQL server to oracle migrations. There is no way to migrate without rewriting the backend code. Too many differences between the 2 databases and more importantly differences between the 2 mind sets of the programmers. Many managers think that the 2 are interchangeable, I have had managers ask me to copy the stored procedures from SQL server and compile them in oracle, not a clue! Toad is by far the best tool on the market for supporting an oracle application. SQL developer is ok but was disappointing compared to toad. I hope that oracle will catch their product up to toad one day but it is not there yet. Have a good day :) chances are if you are migrating to oracle it is for a reason and in order to meet that requirement you will need to rewrite the back end code or you will have many issues.

Answer 2

The language difference listed so far are trivial compared to the logical differences. Anyone can lookup NVL. What's hard to lookup is

DDL

In SQL server you manipulate your schema, anywhere, anytime, with little or no fuss.

In Oracle, we don't like DDL in stored procedures so you have jump through hoops. You need to use EXECUTE IMMEDIATE to perform a DDL function.

Temp Tables

IN SQL Server when the logic becomes a bit tough, the common thing is to shortcut the sql and have it resolved to a temp table and then the next step is done using that temp table. MSSS makes it very easy to do this.

In Oracle we don't like that. By forcing an intermediate result you completely prevent the Optimizer from finding a shortcut for you. BUT If you must stop halfway and persist the intermediate results Oracle wants you to make the temp table in advance, not on the fly.

Locks

In MSSS you worry about locking, you have nolock hints to apply to DML, you have lock escalation to reduce the count of locks.

In Oracle we don't worry about these in that way.

Read Commited

Until recently MSSS didn't fully handle Read Committed isolation so you worried about dirty reads.

Oracle has been that way for decades.

etc

MSSS has no concept of Bitmap indexes, IOT, Table Clusters, Single Table hash clusters, non unique indexes enforcing unique constraints....

Answer 3

I get the impression most answers focus on migrating an entire database or just point to some differences between T-SQL and PL/SQL. I recently had the same problem. The Oracle database exists, but I need to convert a whole load of T-SQL scripts to PL/SQL.

I installed Oracle SQL Developer and ran the Translation Scratch Editor (Tools > Migration > Translation Scratch Editor).

Then, just enter your T-SQL, choose the correct translation in the dropdownlist (it should default to 'T-SQL to PL/SQL'), and convert it.

Answer 4

I have to things to mention.

1) When I worked on Oracle 8, you could not do "Select @Result", you had to instead use the dummy table as follows "Select @Result from dual". Not sure if that ridiculousness still exists.

2) In the Oracle world they seem to love cursors and you better read up on them, they use them all the time AFAICS.

Good luck and enjoy,

it is not that different to MS SQL. Thankfully, I do not have to work with it anymore and I am back in the warm comfort of MS tools.

Answer 5

If you replace your ISNULL and NVL nonsense with COALESCE, it'll work in T-SQL and PL/SQL!

Answer 6

The most important differences for plain T-SQL are:

• NVL replaces ISNULL
• SYSDATE replaces GETDATE()
• CONVERT is not supported
• Identity columns must be replaced with sequences <-- not technically T- or PL/ but just SQL

Note. I assume you do not use the deprecated SQL Server *= syntax for joins

@jodonell: The table you link to is a bit outdated, oracle has become somewhat more standards compliant after 9i supporting things like CASE and ANSI outer joins