Union

Combine rows from multiple tables, views, or query results into a single unified dataset.

The Union feature in DBCode lets you stack rows from two or more datasets into a single result — similar to a SQL UNION ALL, but performed entirely in the client without writing any SQL. Union tables, views, or the results of any query, within the same database, across different databases, or even across different servers and connection types.

Starting a Union

There are two ways to start a union:

From the DB Explorer

  1. Single Selection: Right-click on a table or view in the DB Explorer and select Union…. A picker will appear allowing you to browse and select additional tables to union with.

  2. Multi-Selection: Hold Ctrl (Windows/Linux) or Cmd (macOS) and click to select two or more tables or views, then right-click and select Union….

Row Limit Options

When performing a union from the DB Explorer, you’ll be prompted to select a row limit:

  • All rows - Load the entire dataset from each table
  • First 1,000 rows - Quick union on a sample
  • First 10,000 rows - Moderate sample size
  • First 100,000 rows - Larger sample for thorough analysis

From the Results Panel

Union the results of any SQL query directly from the Results Panel:

  • Context menu - Right-click on a result tab and select Union With… to enter selection mode, then click additional tabs to include.
  • Multi-select - Hold Ctrl (Windows/Linux) or Cmd (macOS) and click two or more tabs, then right-click and select Union.
  • Convert - Right-click on a stacked or join tab and select Convert to Union to re-combine as a union instead.

Understanding the Results

The union result opens in a grid (either a dedicated editor tab from the DB Explorer, or a new result tab in the Results Panel). The grid has all the standard features — sorting, filtering, exporting, charting, and more.

Union results grid showing combined data from customers_prod and customers_staging
The union result stacks rows from both tables with a Source column identifying the origin of each row

Column Alignment

Columns from each source are aligned by name (case-insensitive). This means:

  • Columns with the same name across sources are merged into a single column
  • Columns that exist in one source but not another will contain NULL for the rows from the other source
  • The column order follows the first source, with any additional columns from subsequent sources appended

Source Identification

A Source column is automatically added as the first column, showing which table or query each row originated from. This makes it easy to filter, sort, or group by source. When unioning across different connections, the connection name is included in the source label.

Cross-Server and Cross-Database Unions

One of the most powerful aspects of the Union feature is the ability to combine data from completely different servers and database systems:

  • Same server, different databases - Union tables across schemas or databases on the same server
  • Different servers, same database type - Combine data from production and staging
  • Different database systems - Union a MySQL table with a PostgreSQL table, or SQL Server with Oracle

This is invaluable for:

  • Aggregating similar data from multiple environments or regions
  • Combining reference data scattered across different systems
  • Building consolidated views across microservices with different databases
  • Quick ad-hoc reporting across heterogeneous data sources