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The QUOTENAME and CONCAT_WS string functions

Antonios Chatzipavlis
Sunday 14 June 2020

Overview

Αν και είναι ένα μικρό άρθρο αυτό, εντούτοις θεώρησα ότι πρέπει να το γράψω καθώς βλέπω ότι κάποιοι ταλαιπωρούνται αδίκως όταν γράφουν κώδικα ειδικά όταν αυτός πρέπει να περιέχει object names πχ tables, fields, views, stored procedures.

Sample

Ας πάρουμε ένα απλό παράδειγμα. Έστω ότι θέλουμε να δημιουργήσουμε ένα script που να δημιουργεί select statements για όλα τα table και views που έχω σε μία databases.

Η απλούστερη λύση είναι να ρωτήσουμε το INFORMATION_SCHEMA.TABLES view

SQL Script

SELECT *
FROM INFORMATION_SCHEMA.TABLES;

Οι περισσότεροι για να ικανοποιήσουν την ανάγκη αυτή θα γράψουν το παρακάτω:

SQL Script

SELECT 'SELECT * FROM ' + '[' + TABLE_SCHEMA + '].[' + TABLE_NAME + ']' AS selectstm
FROM INFORMATION_SCHEMA.TABLES;
Result
selectstm
SELECT * FROM [Sales].[OrdersXXL]
SELECT * FROM [Sales].[CustomersEnlarge]
SELECT * FROM [dbo].[tbl_T]
SELECT * FROM [Sales].[OrdersEnlarge]
SELECT * FROM [HR].[Employees]
SELECT * FROM [Production].[Suppliers]
SELECT * FROM [Production].[Categories]
SELECT * FROM [Production].[Products]
SELECT * FROM [Sales].[Customers]
SELECT * FROM [Sales].[Shippers]

QUOTENAME

Αντί όμως για αυτό θα μπορούσαν να κάνουν χρήση της QUATENAME string function όπως παρακάτω:

SQL Script

SELECT 'SELECT * FROM ' + QUOTENAME(TABLE_SCHEMA)+'.' + QUOTENAME(TABLE_NAME) AS selectstm
FROM INFORMATION_SCHEMA.TABLES;
Result
selectstm
SELECT * FROM [Sales].[OrdersXXL]
SELECT * FROM [Sales].[CustomersEnlarge]
SELECT * FROM [dbo].[tbl_T]
SELECT * FROM [Sales].[OrdersEnlarge]
SELECT * FROM [HR].[Employees]
SELECT * FROM [Production].[Suppliers]
SELECT * FROM [Production].[Categories]
SELECT * FROM [Production].[Products]
SELECT * FROM [Sales].[Customers]
SELECT * FROM [Sales].[Shippers]

CONCAT_WS

Αλλά επειδή δεν θέλω να βλέπω και να βάζω πολλά + μπορώ να χρησιμοποιήσω και την CONCAT_WS string functions και να κάνω την ζωή μου καλύτερη.

Note

H CONCAT_WS είναι διαθέσιμη από τον SQL Server 2017.

SQL Script

SELECT 'SELECT * FROM ' + CONCAT_WS('.',QUOTENAME(TABLE_SCHEMA),QUOTENAME(TABLE_NAME)) AS selectstm
FROM INFORMATION_SCHEMA.TABLES;
Result
selectstm
SELECT * FROM [Sales].[OrdersXXL]
SELECT * FROM [Sales].[CustomersEnlarge]
SELECT * FROM [dbo].[tbl_T]
SELECT * FROM [Sales].[OrdersEnlarge]
SELECT * FROM [HR].[Employees]
SELECT * FROM [Production].[Suppliers]
SELECT * FROM [Production].[Categories]
SELECT * FROM [Production].[Products]
SELECT * FROM [Sales].[Customers]
SELECT * FROM [Sales].[Shippers]

Another sample

Εκτός όμως από αυτή την χρήση υπάρχουν και άλλες όπως για παράδειγμα το παρακάτω όπου θέλω να έχω το contact name και το contact title σε μια νέα κολώνα με την μορφή contactname (contacttitle).

SQL Script

SELECT contactname,contacttitle, CONCAT_WS(' ',contactname , QUOTENAME(contacttitle,'()')) as ContactNameTitle
FROM SALES.Customers
Result
contactname contacttitle ContactNameTitle
Allen, Michael Sales Representative Allen, Michael (Sales Representative)
Hassall, Mark Owner Hassall, Mark (Owner)
Strome, David Owner Strome, David (Owner)
Cunningham, Conor Sales Representative Cunningham, Conor (Sales Representative)
Higginbotham, Tom Order Administrator Higginbotham, Tom (Order Administrator)
Poland, Carole Sales Representative Poland, Carole (Sales Representative)
Bansal, Dushyant Marketing Manager Bansal, Dushyant (Marketing Manager)
Ilyina, Julia Owner Ilyina, Julia (Owner)
Raghav, Amritansh Owner Raghav, Amritansh (Owner)
Culp, Scott Accounting Manager Culp, Scott (Accounting Manager)

Note

H QUOTENAME δέχετε ακόμα μια παράμετρο την 'quote_character'
Is a one-character string to use as the delimiter. Can be a single quotation mark ( ' ), a left or right bracket ( [] ), a double quotation mark ( " ), a left or right parenthesis ( () ), a greater than or less than sign ( >< ), a left or right brace ( {} ) or a backtick ( ` ). NULL returns if an unacceptable character is supplied. If quote_character is not specified, brackets are used.

Conclusion

Είδαμε μερικά παραδείγματα για το πως μπορούμε να χρησιμοποιήσουμε αυτές, υπάρχουν πολλά ακόμα. Αυτό που λέω πάντα είναι ότι χρησιμοποιούμε πάντα αυτό που έχει την καλύτερη απόδοση στην εκάστοτε περίπτωση.


Antonios Chatzipavlis

Antonios Chatzipavlis

Antonios Chatzipavlis

Antonios Chatzipavlis is a highly experienced Data Solutions Consultant and Trainer. He has been working in the IT industry since 1988, holding various roles such as senior developer, IT Manager, Data & AI Solutions Architect and Consultant.

Since 1995, Antonios has focused on modern technologies and software development tools, primarily by Microsoft. He has specialized in Data & AI since 2000, with expertise in Microsoft Data Platform (SQL Server, Azure SQL Databases, Azure Synapse Analytics, Microsoft Fabric, Power BI, AI) and Databricks.

Antonios is also a Microsoft Certified Trainer (MCT) for over 25 years, has been recognized as a Microsoft Most Valuable Professional (MVP) in Data Platform since 2010 and he is in the Data Expert 40 Powerlist 2024 by Boussias. He is the co-founder and visionary behind XLYTiCA, a company dedicated to Data & AI solutions.

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