Скачать или смотреть How to Group and Count Data by Column in ORACLE SQL

A comprehensive guide to group and count data by column using ORACLE SQL, including step-by-step instructions and key SQL queries.
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How to Group and Count Data by Column in ORACLE SQL

When working with databases, particularly with ORACLE SQL, you may often need to analyze data effectively by grouping and counting records. This is especially vital when dealing with multiple tables that contain related information. In this guide, we will explore how to achieve this by examining two tables and constructing a query that meets specific criteria.

Understanding the Problem

Let's visualize our problem using two tables:

Table A lists unique IDs associated with codes and timestamps.

Table B connects these IDs to additional information, including their status and associated values.

The Task

We want to accomplish the following tasks:

Count how many records are present each day.

Count the occurrence of each distinct code.

Present this data in a format where each row represents a day, specifically filtering for statuses "0" or "1" and only for records between specific dates (from November 30, 2020, to February 6, 2021).

Expected Result

The output should display a summary table that looks like this:

datesum_of_this_daycode_1code_2code_3...code_z2020-11-30355010...x2020-11-31606512...x.....................2021-02-06476512...xStep-by-Step Solution

Now, let’s break down the solution into manageable sections:

Step 1: Filter Rows

First, we need to filter the data according to the specified conditions:

Status must be either "0" or "1".

Only include records dated between November 30, 2020, and February 6, 2021.

Step 2: Create an Intermediate Table

We can create a Common Table Expression (CTE) to filter our records from both tables based on the conditions stated:

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

Step 3: Pivot for Distinct Codes

Next, we'll need to count the distinct codes for each day. We will use the PIVOT feature in SQL to achieve this:

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

Step 4: Count Total Codes Daily

We will also create another CTE to count the total number of codes per day:

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

Step 5: Combine Results

Finally, we can join the results from our pivot_table and every_day_cnt to get our final output:

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

Conclusion

By following the steps outlined above, you can effectively group and count data by column in ORACLE SQL. This method not only provides a clear summary of your data over a specified period but also utilizes SQL’s powerful pivoting and filtering capabilities. Whether for daily reporting or deeper insights, mastering this technique is essential for any SQL practitioner.

Happy querying!