One of the string functions in MySQL is STRCMP(). This function allows you to compare two strings according to their sort order.
The function accepts two arguments. Each argument is the string to compare. It returns either 1, -1, or 0, depending on whether the first string is larger, smaller, or the same size as the second string, according to sort order.
This article aims to help you understand the DIFFERENCE() function, which is a T-SQL function available in SQL Server, Azure, etc.
The key to understanding the DIFFERENCE() function is to understand how Soundex works (or in the context of SQL Server, how the SOUNDEX() function works). This is because the DIFFERENCE() function returns the difference between the Soundex values between two strings.
A Soundex value is four characters long. If two words sound the same, they will share the same four character Soundex value. If they sound similar (but not the same), their Soundex values might share some characters but not all. For example, their Soundex values might have two characters the same and two that are different. If two words sound completely different, none of the characters in their respective Soundex values will be the same.
The DIFFERENCE() function returns a value that ranges from 0 through 4. This value represents the number of characters in the Soundex values that are the same. 0 indicates weak or no similarity, and 4 indicates strong similarity or the same values.
Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English. It was developed and patented in 1918 and 1922.
One of the functions available in SQL Server is the SOUNDEX() function, which returns the Soundex code for a given string.
One of the many MySQL string functions is the SOUNDEX() function. This function returns a Soundex string from a given string. If two words sound the same, they should have the same Soundex string. If two words sound similar, but not exactly the same, their Soundex string might look similar but not exactly the same.
This article contains a bunch of Soundex examples to demonstrate how the SOUNDEX() function works in MySQL.
If you need to convert a number from decimal to octal (base 8), two functions come to mind if you’re using MySQL. One function is specifically for doing octal conversions, the other is for doing conversions between different bases. These are as follows:
OCT()CONV()More about these two functions below.
If you use Oracle Database or MySQL, you’re lucky enough to have the LPAD() and RPAD() functions, which allow you to pad a string with a given character (or characters) to its left and/or right.
However, SQL Server (or more precisely, T-SQL), doesn’t include these functions. So if you need some left padding, you’ll need to improvise.
This article presents four options for padding a number with leading zeros in SQL Server. So you can do stuff like turn 7 into 007. Three of these options work on strings, so you can also apply padding to textual data.
Sometimes you need to pad a string with spaces. Or perhaps you’ll pad it with another character. Sometimes you need to pad it on the left. Other times you need to pad it on the right. Or maybe you need to pad it on both sides.
All of the above can be done in MySQL using the LPAD() and/or RPAD() string functions.
When working with MySQL, you might occasionally encounter situations where you need to pad a bunch of numbers with leading zeros.
Perhaps you have a requirement that all numbers have three digits, but in the data you’ve been supplied, the numbers range from a single digit, to two, and maybe three digits. Your requirement might be to pad all numbers with leading zeros, but only to make up for any shortfall in the three digit requirement.
The LPAD() function does exactly what you want in this scenario.
In SQL Server, you can use the T-SQL REPLACE() function to replace all instances of a given string with another string. For example, you can replace all occurrences of a certain word with another word.
The MySQL REPLACE() function enables you to replace all occurrences of a substring with another string. It allows you to do things like, replace all occurrences of one word with another word, etc.
This article demonstrates its usage.