How to Use LIKE in Oracle SQL to Match Values from Two Different Tables

Description:
Discover how to effectively use Oracle SQL's INNER JOIN and LIKE clause to fetch complete values from one table based on the pattern of another table.
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This video is based on the question https://stackoverflow.com/q/65401930/ asked by the user 'Kostas75' ( https://stackoverflow.com/u/4291851/ ) and on the answer https://stackoverflow.com/a/65401945/ provided by the user 'GMB' ( https://stackoverflow.com/u/10676716/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving the Problem of Matching Table Values in Oracle SQL

When working with databases, we often encounter situations where we need to relate records across different tables. One common scenario is when you have a known value in one table that is part of a larger, unique value in another table. This guide will explain how to achieve this in Oracle SQL with a focus on LIKE and joins.

Understanding the Problem

Suppose we have two tables in our Oracle Database:

Table 1 (table1) contains a column with a known value (let's call it value1). For example:

value1: 4649843545945894537

Table 2 (table2) contains a column with the complete value (let's refer to it as value2), which includes a random digit appended to value1. For instance:

value2: 46498435459458945374 (where 4 is the random digit)

Our goal is to find the complete value (value2) from table2 based on the known value (value1) from table1. More specifically, we want to use SQL to select the complete value2 where it matches value1 followed by any character.

The Solution Explained

To efficiently fetch the value2 based on value1, we can utilize an INNER JOIN with the LIKE operator in our SQL query. Below are two methods to achieve this based on whether our data is stored as strings or numbers.

Method 1: Using LIKE with Strings

If both value1 and value2 are stored as strings, we can proceed with the following SQL query:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

Here, we leverage the LIKE operator to find value2 that starts with value1 followed by any one character (indicated by the underscore _).

The INNER JOIN ensures that only matching records are returned, combining data from both table1 and table2.

Method 2: Using Arithmetic with Numbers

If value1 and value2 are stored as numbers, we can simplify the relationship using arithmetic operations:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

This approach divides value2 by 10, effectively removing the last digit, and allows us to directly compare it with value1.

By using the FLOOR function, we ensure that the comparison remains accurate, handling any discrepancies from the division.

Conclusion

In summary, whether your data is in string format or numerical format, Oracle SQL provides effective methods to link records across tables. By using the LIKE operator with INNER JOIN or simple arithmetic, you can easily retrieve data that aligns with your needs.

Implementing either of these solutions will help you efficiently fetch the complete value you're looking for, enhancing your database query skills and expanding your capabilities in managing data relationships.

Feel free to try these methods in your Oracle SQL environment and see how they work for your specific data sets!