#STRING_AGG function

[thedbahub]

Concatenating Row Values into a Single String in SQL Server

Concatenating text from multiple rows into a single text string in SQL Server can be achieved using different methods, depending on the version of SQL Server you are using. The most common approaches involve using the FOR XML PATH method for older versions, and the STRING_AGG function, which was introduced in SQL Server 2017. I’ll explain both methods. Using STRING_AGG (SQL Server 2017 and…

[izicodes]

C# x SQL ‘Search A User Page’ project | 23rd Jun ‘22

Good afternoon!

Another day working on my late late late project! I think I’m having a really bad day with my project! Just the last piece of my project which is to add a ‘Roles’ column to the table at the end:

Easier said than done! The leading developer on the team doesn’t even know how to do it, and he was the one who gave me the project!? (⊙_⊙)？ But in the end, it is reassuring because if he doesn’t know, then I guess it is just hard overall!

The other columns of the table were easy to make in SMSS because it’s just linking 1 or 2 tables but this ‘Roles’ column is made from 4 different tables and, in the end, you have to merge the rows with the same names into one row – turns out the function I wanted to use ‘STRING_AGG()’ if for an older(?) version of SMSS, so that is why it was impossible to get it right from what I, and Mike, have been taught. There is a new function ‘STUFF()’ that does the same job of string concatenation in SQL but… me and Mike kept getting the syntax wrong and the query would execute something completely different. In the end, we were left with this:

The query executes all the roles in multiple rows and is not merged into one! ￣へ￣

Almost called quits on this project so many times! I just need to get this done by Friday preferably because I have online classes all next week from 9am – 4pm and I would be very busy, I would have to put aside this project to focus on the classes – that is if I don’t get this done this weekend.

[andnahas]

Toad for sql server null

Therefore, if we want to retain the rows with null values, we can use ISNULL() to replace the null values with another value: SELECT STRING_AGG(ISNULL(TaskCode, 'N/A'), ', ') AS ResultĬat123, N/A, N/A, pnt456, rof789, N/A The COALESCE() Function However, this could also cause issues, depending on what the data is going to be used for. In many cases, this is a perfect result, as our result set isn’t cluttered up with null values. So the three rows containing null values aren’t returned. So if we use this function with the above sample data, we’d end up with three results instead of six: SELECT STRING_AGG(TaskCode, ', ') AS Result However, it also eliminates null values from the result set. This function allows you to return the result set as a delimited list. One example of such a function is STRING_AGG(). While this might be a desirable outcome in some cases, in other cases it could be disastrous, depending on what you need to do with the data once it’s returned. In such cases, null values won’t be returned at all. There are some T-SQL functions where null values are eliminated from the result set. That’s because it returns the result using the data type of the first argument. Note that ISNULL() requires that the second argument is of a type that can be implicitly converted to the data type of the first argument. We could also replace it with the empty string: SELECT ISNULL(TaskCode, '') AS Result Like this: SELECT ISNULL(TaskCode, 'N/A') AS Result If we didn’t want the null values to appear as such, we could use ISNULL() to replace null with a different value. We can see that there are three rows that contain null values. Here’s a basic query that returns a small result set: SELECT TaskCode AS Result ISNULL() is a T-SQL function that allows you to replace NULL with a specified value of your choice. That’s what the ISNULL() function is for. But there may also be times where you do want them returned, but as a different value. And there may be times where you do want them returned. See Automate Tasks for more information.When querying a SQL Server database, there may be times where you don’t want null values to be returned in your result set. Tip: You can save this Query Builder file (.tsm) and click Automate to schedule query execution, generate a report of the results, and email the report to colleagues. If you click this for the Fiscal or Academic calendars, you are prompted to revert back to the original version.Īdd additional columns and complete the query. Click to view the dates.If you select a Custom calendar, you can customize the dates.Academic or Custom-For the Period name, updating the name updates the name value in the Date Range Values list.Fiscal-For Fiscal calendar type, you can select Normal, or two four week periods and one 5 week period that can be defined as 4/4/5, 5/4/4, or 4/5/4.Review the following for additional information about the Calendar Editor: If you select a calendar type other than Gregorian, you can click to edit the selected calendar. Select the type of calendar to use for the date range values. Review the following for additional information: Calendar Select the Where Condition field below the date column and click. Select a column with a date data type from a table in the Diagram tab. The following date range commands are available and can also be used in the Editor: Toad inserts the correct SQL between these quotes when you execute the query. The criteria is empty and contains two single quotes without a space. WHERE (sales.ord_date = '' /*Last year*/ ) The following displays the revised query: This ensures that your query is valid regardless of the date. With Toad, you simply select Last year to dynamically insert the correct SQL. WHERE (sales.ord_date BETWEEN ' 00:00:00' In the past, you hard coded the dates to create the following statement: You need to create a query that retrieves a list of the orders that were placed last year. If you want to view the syntax of the date range so you can copy it to another application, click the date range link in the Query tab, as illustrated in the following: Note: The date range format is specific to Toad. Identifying the actual date range to use is time consuming, confusing, and is often error prone. When writing a query, you frequently need to retrieve data from a range of dates such as the last week, month, or quarter. Storage Performance and Utilization Management.Information Archiving & Storage Management.Hybrid Active Directory Security and Governance.Starling Identity Analytics & Risk Intelligence.One Identity Safeguard for Privileged Passwords.

[gregdodd]

Distinct List in String_Agg

How do you get a distinct list of strings when using String_Agg?

SQL introduced the new STRING_AGG feature in SQL 2017, and it works just like it suggests it would: it’s an aggregate function that takes all of the string values and joins them together with a separator. To see how it works, I’m using the StackOverflow users table, and let’s say we want to create a list of Display Names and we’re going to group it based on Location: SELECT…

[erpqna]

Split table column value into multiple rows using SQL in SAP HANA

Split table column value into multiple rows using SQL in SAP HANA

Introduction

In this post I would like to focus on the similar scenario, but this time the challenge will be to do the same not for variable but for table column. SAP HANA enables STRING_AGG function for concatenating values from multiple lines into single string, however doing opposite is quite challenging.

Read More: SAP HANATEC 12 Certification Preparation Guide

Scenario

In my…

[infinitejoke]

SELECT, Beyond the Basics

I admit, I’m somewhat spoiled by ORM tools -- most notably ActiveRecord -- which hide database queries behind layers of objects and method chains.

This makes me lag behind somewhat with the assignments for my DB class, in which I have to write raw SQL.

In this post, I’m going to put together some info on PostgreSQL’s SELECT, going beyond the elementary stuff.

Set operations

UNION, INTERSECT, and EXCEPT share the same general form:

SELECT ... FROM ... (UNION | INTERSECT | EXCEPT) SELECT ... FROM ...

By default, the operations remove duplicate rows from the result set. The behavior can be changed by appending ALL:

UNION ALL does not discard duplicate rows, and therfore performs better.

With INTERSECT ALL, a row that has m duplicates in the left table and n duplicates in the right table will appear min(m,n) times in the result set.

With EXCEPT ALL, a row that has m duplicates in the left table and n duplicates in the right table will appear max(m-n,0) times in the result set.

Multiple clauses in the same SELECT statement are evaluated left to right. INTERSECT has higher precedence than UNION.

Ordering

ORDER BY sorts the result rows according to the specified expressions. Rows that are equal according to the leftmost expression are compared according to the next expression and so on. If they are equal according to all expressions, the order is implementation-dependent.

An expression can be a number, referring to the ordinal (left-to-right) position of the output column, e.g. SELECT city, temp FROM weather ORDER BY 2.

It is possible to specify columns that do not appear in the output list, e.g. SELECT city FROM weather ORDER BY temp.

A name that matches both an output column name and an input column name is interpreted as the output column name.

Ordering options apply only to the expression they follow: ORDER BY 1, 2 DESC is not the same as ORDER BY 1 DESC, 2 DESC.

An expression can be a CASE, for example:

SELECT * FROM people ORDER BY CASE gender WHEN 'female' THEN name ELSE last_name END DESC;

Aggregate Functions

The main ones are avg, count, max, min, sum. A usage example from the documentation is:

SELECT max(temp) FROM weather;

The first limitation to consider is that the WHERE clause is evaluated before aggregate functions are computed (it determines which rows will be included in the aggregate calculation). It means that something like SELECT city FROM weather WHERE temp = max(temp) does not work.

What we need is an independent computation, or a subquery:

SELECT city FROM weather WHERE temp = (SELECT max(temp) FROM weather);

Aggregate functions can be computed for groups of rows specified by GROUP BY:

SELECT city, MAX(temp) FROM weather GROUP BY city;

(Returns every city along with the maximum temperature registered in it.)

Unlike WHERE, a HAVING clause selects group rows after aggregates and groups are computed, making it useful for filtering results:

SELECT city, max(temp) FROM weather GROUP BY city HAVING max(temp) < 40;

When the output of a function depends on the order of inputs, an ORDER BY can be added after the last argument:

SELECT string_agg(city, ', ' ORDER BY date DESC) FROM weather;

PostgreSQL 9.4 added support for a FITLER (WHERE ...) clause that specifies which rows are fed to the aggregate function:

SELECT count(*) AS unfiltered, count(*) FILTER (WHERE i < 5) AS filtered FROM generate_series(1,10) AS s(i);

unfiltered | filtered ------------+---------- 10 | 4