MYSQL: Validate Input Values in Specific Format within a FUNCTION

i have one question with regard to MYSQL. I want to create a function that is able to check whether an Input is given in a specific format.

i have one question with regard to MYSQL. I want to create a function that is able to check whether an Input is given in a specific format.

The output should be in the following shape:

***x x (a) n (n) (n) (n)
with :
x = letters and numbers
n = numbers
a = letters
brackets = optional Values***

my code is written below this.

CREATE FUNCTION validate_of_number(testnumber VARCHAR(7))
RETURNS INT
DETERMINISTIC
RETURN
    CASE
        WHEN
            (SELECT * FROM flightexecution WHERE FlightNo REGEXP 
            '^[[:alnum:]+[:alnum:]] + [[:alpha:]|''] + [:digit:] + 
            [[:digit:]|''] + [[:digit:]|''] + [[:digit:]|'']') > 0
            Then 1
            Else 0
            END;`

However, it does not work and i don´t know why. The Output is just a 'OK' without any further information.

SQL Full Course - SQL Tutorial For Beginners - MySQL Essentials - SQL Training

SQL Full Course - SQL Tutorial For Beginners - MySQL Essentials - SQL Training

This SQL Full Course video will cover all the topics of SQL starting from scratch. This video is great for beginners who want to learn SQL and for advanced people to brush up their skills.


Thanks for watching

If you liked this post, share it with all of your programming buddies!

Follow us on Facebook | Twitter

Learn More

The Complete SQL Bootcamp

The Ultimate MySQL Bootcamp: Go from SQL Beginner to Expert

The Complete Oracle SQL Certification Course

MySQL Databases With Python Tutorial

SQL vs NoSQL or MySQL vs MongoDB

MySQL Database Tutorial for Beginners to Advanced Part 1/2

An Introduction to Queries in MySQL

How To Troubleshoot MySQL Queries?

SQL with MySQL - Complete Tutorial for Beginners

Build a Basic CRUD App with PHP and MySQL

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.

Thanks for reading. If you liked this post, share it with all of your programming buddies!

Originally published on https://dzone.com


SQL with MySQL - Complete Tutorial for Beginners

SQL with MySQL - Complete Tutorial for Beginners

Complete SQL tutorial for beginners. Learn to query MySQL databases in no time. Includes exercises & cheat sheet.

This is my brand-new SQL tutorial for beginners. In this course, we’ll be using MySQL Workbench but you can use any other clients to connect to MySQL. By the end of this course, you’ll be able to retrieve, insert, update and delete data in a MySQL database. These are the essential skills that every software developer or data scientist must know. More specifically, we’ll be covering:

  • Basics of relational databases
  • Retrieving data
  • Sorting and filtering data
  • Logical operators
  • Limiting data
  • Joins (inner, outer, self, cross, natural)
  • Unions
  • Inserting, updating and deleting data
  • Subqueries
  • And more…

You don’t need any prior experience to take this SQL course. Simply follow along and complete all the exercises and you’ll be able to write powerful queries to extract interesting insights from your dad.

While I’ve created this course with MySQL, most of the SQL code you learn in this course will work with other database management systems such as SQL Server, Oracle, etc.


Learn More

The Complete SQL Bootcamp

The Ultimate MySQL Bootcamp: Go from SQL Beginner to Expert

The Complete Oracle SQL Certification Course

MySQL Databases With Python Tutorial

SQL vs NoSQL or MySQL vs MongoDB

The basics of NoSQL databases — and why we need them

MySQL Database Tutorial for Beginners to Advanced Part 1/2

How To Manage an SQL Database

Why We Moved From NoSQL MongoDB to PostgreSQL?

Originally published at https://www.youtube.com/watch?v=7S_tz1z_5bA