Complex query containing multiple joins is not executing right outer join

I'm writing a query with multiple joins where I want every user to show entries against all category Types. When I execute the query below only 1 record is returned because the employee u.employee_id = "0079-P" has only worked on 1 project but I want to get data for all the category_types with users workhours displayed as null for the categories he didn't work on.

I'm writing a query with multiple joins where I want every user to show entries against all category Types. When I execute the query below only 1 record is returned because the employee u.employee_id = "0079-P" has only worked on 1 project but I want to get data for all the category_types with users workhours displayed as null for the categories he didn't work on.

Select u.employee_id As Employee_ID, u.user_name As UserName, COALESCE(primaryDept.ctd_name, primaryProj.ctd_name) As PrimaryDeptOrProj, region.region_name As Region, categoryType.ctd_id, categoryType.ctd_name, SUM(tsdd.workhours) 
    From users u 
    LEFT JOIN category_type_details primaryDept ON u.user_primary_department = primaryDept.ctd_id
    LEFT JOIN category_type_details primaryProj ON u.user_primary_project = primaryProj.ctd_id
    LEFT JOIN regions region ON u.region_id = region.region_id
    LEFT JOIN timesheets ts ON u.user_id = ts.timesheet_user
    INNER JOIN timesheet_mr tsmr ON ts.timesheet_caller = tsmr.tsmr_id
    INNER JOIN timesheet_details tsd ON ts.timesheet_id = tsd.tsd_timesheet_id
    INNER JOIN timesheet_day_details tsdd ON tsd.tsd_id = tsdd.tsd_id
    RIGHT OUTER JOIN category_type_details categoryType ON tsd.tsd_category_type_id = categoryType.ctd_id
    WHERE tsmr.tsmr_id = 14 and u.employee_id = "0079-P"
    GROUP BY u.user_id, tsd.tsd_category_type_id;

I tried this query with variations and it returns 1 record in any case. Any help, suggestion or sense of direction is much appreciated.

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What are the differences between Standard SQL and Transact-SQL?

What are the differences between Standard SQL and Transact-SQL?

In this article, we'll explain syntax differences between standard SQL and the Transact-SQL language dedicated to interacting with the SQL

#1 Names of Database Objects

In relational database systems, we name tables, views, and columns, but sometimes we need to use the same name as a keyword or use special characters. In standard SQL, you can place this kind of name in quotation marks (""), but in T-SQL, you can also place it in brackets ([]). Look at these examples for the name of a table in T-SQL:

CREATE TABLE dbo.test.“first name” ( Id INT, Name VARCHAR(100));
CREATE TABLE dbo.test.[first name]  ( Id INT, Name VARCHAR(100));

Only the first delimiter (the quotation marks) for the special name is also part of the SQL standard.

What Is Different in a SELECT Statement?#2 Returning Values

The SQL standard does not have a syntax for a query returning values or values coming from expressions without referring to any columns of a table, but MS SQL Server does allow for this type of expression. How? You can use a SELECT statement alone with an expression or with other values not coming from columns of the table. In T-SQL, it looks like the example below:

SELECT 12/6 ;

In this expression, we don’t need a table to evaluate 12 divided by 6, therefore, the FROM statement and the name of the table can be omitted.

#3 Limiting Records in a Result Set

In the SQL standard, you can limit the number of records in the results by using the syntax illustrated below:

SELECT * FROM tab FETCH FIRST 10 ROWS ONLY

T-SQL implements this syntax in a different way. The example below shows the MS SQL Server syntax:

SELECT * FROM tab ORDER BY col1 DESC OFFSET 0 ROWS FETCH FIRST 10 ROWS ONLY;

As you notice, this uses an ORDER BY clause. Another way to select rows, but without ORDER BY, is by using the TOP clause in T-SQL:

SELECT TOP 10 * FROM tab;
#4 Automatically Generating Values

The SQL standard enables you to create columns with automatically generated values. The syntax to do this is shown below:

CREATE TABLE tab (id DECIMAL GENERATED ALWAYS AS IDENTITY);

In T-SQL we can also automatically generate values, but in this way:

CREATE TABLE tab (id INTEGER IDENTITY);
#5 Math Functions

Several common mathematical functions are part of the SQL standard. One of these math functions is CEIL(x), which we don’t find in T-SQL. Instead, T-SQL provides the following non-standard functions: SIGN(x), ROUND(x,[,d]) to round decimal value x to the number of decimal positions, TRUNC(x) for truncating to given number of decimal places, LOG(x) to return the natural logarithm for a value x, and RANDOM() to generate random numbers. The highest or lowest number in a list in the SQL standard is returned by MAX(list) and MIN(list) functions, but in Transact-SQL, you use the GREATEST(list) and LEAST(list) functions.

T-SQL function ROUND:

SELECT ROUND(col) FROM tab;

#6 Aggregate Functions

We find another syntax difference with the aggregate functions. The functions COUNT, SUM, and AVG all take an argument related to a count. T-SQL allows the use of DISTINCT before these argument values so that rows are counted only if the values are different from other rows. The SQL standard doesn't allow for the use of DISTINCT in these functions.

Standard SQL:
SELECT COUNT(col) FROM tab;

T-SQL:
SELECT COUNT(col) FROM tab;

SELECT COUNT(DISTINCT col) FROM tab;

But in T-SQL we don’t find a population covariance function: COVAR_POP(x,y), which is defined in the SQL standard.

#7 Retrieving Parts of Dates and Times

Most relational database systems deliver many functions to operate on dates and times.

In standard SQL, the EXTRACT(YEAR FROM x) function and similar functions to select parts of dates are different from the T-SQL functions like YEAR(x) or DATEPART(year, x).

There is also a difference in getting the current date and time. Standard SQL allows you to get the current date with the CURRENT_DATE function, but in MS SQL Server, there is not a similar function, so we have to use the GETDATE function as an argument in the CAST function to convert to a DATE data type.

#8 Operating on Strings

Using functions to operate on strings is also different between the SQL standard and T-SQL. The main difference is found in removing trailing and leading spaces from a string. In standard SQL, there is the TRIM function, but in T-SQL, there are several related functions: TRIM (removing trailing and leading spaces), LTRIM (removing leading spaces), and RTRIM (removing trailing spaces).

Another very-often-used string function is SUBSTRING.

The standard SQL syntax for the SUBSTRING function looks like:

SUBSTRING(str FROM start [FOR len])

but in T-SQL, the syntax of this function looks like:

SUBSTRING(str, start, length)

There are reasons sometimes to add values coming from other columns and/or additional strings. Standard SQL enables the following syntax to do this:

As you can see, this syntax makes use of the || operator to add one string to another.

But the equivalent operator in T-SQL is the plus sign character. Look at this example:

SELECT col1 + col2  FROM tab;

In SQL Server, we also have the possibility to use the CONCAT function concatenates a list of strings:

SELECT CONCAT(col1, str1, col2, ...)  FROM tab;

We can also repeat one character several times. Standard SQL defines the function REPEAT(str, n) to do this. Transact-SQL provides the REPLICATE function. For example:

SELECT  REPLICATE(str, x);

where x indicates how many times to repeat the string or character.

#9 Inequality Operator

During filtering records in a SELECT statement, sometimes we have to use an inequality operator. Standard SQL defines <> as this operator, while T-SQL allows for both the standard operator and the != operator:

SELECT col3 FROM tab WHERE col1 != col2;
#10 ISNULL Function

In T-SQL, we have the ability to replace NULL values coming from a column using the ISNULL function. This is a function that is specific to T-SQL and is not in the SQL standard.

SELECT ISNULL(col1) FROM tab;
Which Parts of DML Syntax Are Different?

In T-SQL, the basic syntax of DELETE, UPDATE, and INSERT queries is the same as the SQL standard, but differences appear in more advanced queries. Let’s look at them.

#11 OUTPUT Keyword

The OUTPUT keyword occurs in DELETE, UPDATE, and INSERT statements. It is not defined in standard SQL.

Using T-SQL, we can see extra information returned by a query. It returns both old and new values in UPDATE or the values added using INSERT or deleted using DELETE. To see this information, we have to use prefixes in INSERT, UPDATE, and DELETE.

UPDATE tab SET col='new value'
OUTPUT Deleted.col, Inserted.col;

We see the result of changing records with the previous and new values in an updated column. The SQL standard does not support this feature.

#12 Syntax for INSERT INTO ... SELECT

Another structure of an INSERT query is INSERT INTO … SELECT. T-SQL allows you to insert data from another table into a destination table. Look at this query:

INSERT INTO tab SELECT col1,col2,... FROM tab_source;

It is not a standard feature but a feature characteristic of SQL Server.

#13 FROM Clause in DELETE and UPDATE

SQL Server provides extended syntax of the UPDATE and DELETE with FROM clauses. You can use DELETE with FROM to use the rows from one table to remove corresponding rows in another table by referring to a primary key and a foreign key. Similarly, you can use UPDATE with FROM update rows from one table by referring to the rows of another table using common values (primary key in one table and foreign key in second, e.g. the same city name). Here is an example:

DELETE FROM Book
FROM Author
WHERE Author.Id=Book.AuthorId AND Author.Name IS NULL;

UPDATE Book
SET Book.Price=Book.Price*0.2
FROM Author
WHERE Book.AuthorId=Author.Id AND Author.Id=12;

The SQL standard doesn’t provide this syntax.

#14 INSERT, UPDATE, and DELETE With JOIN

You can also use INSERT, UPDATE, and DELETE using JOIN to connect to another table. An example of this is:

DELETE ItemOrder FROM ItemOrder
JOIN Item ON ItemOrder.ItemId=Item.Id
WHERE YEAR(Item.DeliveredDate) <= 2017;

This feature is not in the SQL standard.

Summary

This article does not cover all the issues about syntax differences between the SQL standard and T-SQL using the MS SQL Server system. However, this guide helps point out some basic features characteristic only of Transact-SQL and what SQL standard syntax isn’t implemented by MS SQL Server.

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Originally published on https://dzone.com


SQL Tutorial – Learn SQL Programming Online from Experts

This SQL tutorial will help you learn SQL basics, so you can become a successful SQL developer. You will find out what are the SQL commands, syntax, data types, operators, creation & dropping of tables, inserting and selecting query. Through this tutorial you will learn SQL for working with a relational database. Learn SQL from Intellipaat SQL training and fast-track your career.

SQL Tutorial for Beginners

This SQL Tutorial for Beginners is a complete package for how to learn SQL online. In this SQL tutorial , you will learn SQL programming to get a clear idea of what Structured Query Language is and how you deploy SQL to work with a relational database system.

So, a structured query language is a language that is used to operate the relational databases. Some of the major ways in which SQL is used in conjunction with a relational database is for the purposes of storing, retrieving and manipulating of data stored in a relational database.

Check out Intellipaat’s blog to get a fair understanding of SQL Optimization Techniques!

Here we have the list of topics if you want to jump right into a specific one:


Watch this SQL Tutorial for Beginners video:



What is SQL?


The language to communicate with the relational database is the SQL or Structured Query Language. SQL programming helps to operate the relational databases and derive information from it.

Some of the operations that the SQL does include creation of database, fetching, modifying, updating and deleting the rows along with storing, manipulating and retrieving data within the relational database. SQL programming is an ANSI standard language but there are a lot of versions of SQL in usage as well.


Why is SQL programming so widely used?

Structured Query Language or SQL programming is used so extensively for the following reasons.

  • SQL lets you access any data within the relational database
  • You can describe the data in the database using SQL
  • Using SQL you can manipulate the data with the relational database
  • SQL can embed within other languages through SQL modules & libraries
  • SQL lets you easily create and drop databases and tables
  • SQL allows you to create views, functions and stored procedures in databases
  • Using SQL you can set permissions on procedures, tables and views.


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Features of SQL

Here in this section of the SQL tutorial for beginners, we list some of the top features of SQL that make it so ubiquitous when it comes to managing relational databases.

  • SQL is very simple and easy to learn language
  • SQL is versatile as it works with database systems from Oracle, IBM, Microsoft, etc.
  • SQL is an ANSI and ISO standard language for database creation and manipulation
  • SQL has a well-defined structure as it uses long established standards
  • SQL is very fast in retrieving large amounts of data very efficiently
  • SQL lets you manage databases without knowing lot of coding


Applications of SQL

Here in this section of the SQL tutorial we will learn SQL applications that make it so important in a data-driven world where managing huge databases is the norm of the day.

  • SQL is used as a Data Definition Language (DDL) meaning you can independently create a database, define its structure, use it and then discard it when you are done with it
  • SQL is also used as a Data Manipulation Language (DML) which means you can use it for maintaining an already existing database. SQL is a powerful language for entering data, modifying data and extracting data with regard to a database
  • SQL is also deployed as a Data Control Language (DCL) which specifies how you can protect your database against corruption and misuse.
  • SQL is extensively used as a Client/Server language to connect the front-end with the back-end thus supporting the client/server architecture
  • SQL can also be used in the three-tier architecture of a client, an application server and a database which defines the Internet architecture.

Still have queries? Come to Intellipaat’s SQL Community, clarify all your doubts, and excel in your career!

Why should you learn SQL?

Today regardless of the relational databases systems by major corporations like Oracle, IBM, Microsoft and others, the one thing that is common to them is the Structured Query Language or SQL.

So if you learn SQL online then you will be able to pursue a very broad career spanning a lot of roles of responsibilities. Also if you are learning SQL then it is important for a data science career as well since a data scientist will also have to deal with relational databases and query it using the standard language SQL.

Originally published at www.intellipaat.com in the tutorial "SQL Tutorial" on 09 Sept. 2019.