> ## Documentation Index
> Fetch the complete documentation index at: https://ngquct-fix-disconnected-workspace-navigation.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Table Structure
> Browse and edit columns, indexes, foreign keys, triggers, and DDL with a visual structure editor
export const what_0 = "Column, index and key changes"
This is a DDL editor with a grid in front of it. Rename a column, add an index, change a key, and what you get is a pending `ALTER TABLE` you can read before it runs; the table on the server is untouched until you apply it.
Open a table and switch the result view to **Structure**, or right-click it in the sidebar and choose **Show Structure**.
The tabs are **Columns**, **Indexes**, **Foreign Keys**, **Triggers**, **DDL**, and **Parts** (ClickHouse only); the first four carry item counts. A tab the engine has no concept of is hidden: ClickHouse has no Foreign Keys, Redshift no Triggers. Every grid has a filter field, and clicking a header sorts.
## Columns tab
Columns are edited in place. **Nullable**, **Primary Key**, and **Auto Inc** are YES/NO dropdowns; **Primary Key** set to YES forces **Nullable** to NO and holds it there until the key comes back off. **Type** opens a picker of the engine's types by category: search to filter, or type a parametric value such as `VARCHAR(255)` and press Return to use it as written.
Which remaining columns appear is the driver's choice. **Comment** is there on most engines and writes the column comment. MySQL and MariaDB add **Charset**, **Collation**, and **On Update**; **On Update** set to YES on a `TIMESTAMP` or `DATETIME` column adds `ON UPDATE CURRENT_TIMESTAMP` at that column's own precision, so `TIMESTAMP(6)` gets `ON UPDATE CURRENT_TIMESTAMP(6)`.
Add a column with **+** at the right of the status bar or `Cmd+Shift+N`. Select rows and click **-** or press `Delete` to mark them for removal.
Flag **Primary Key** on one column, or several for a composite key in one `PRIMARY KEY (col1, col2)` clause. On an existing table that becomes a drop of the old constraint followed by an add.
Drag a column row to reorder it (MySQL and MariaDB only). That one runs immediately as `ALTER TABLE … MODIFY COLUMN … AFTER` and goes to query history rather than the queue. Dragging is off while unsaved changes exist.
## Indexes tab
| Field | Description |
| ------------- | ---------------------------------------------------------------------------------------------------------------------- |
| **Columns** | Indexed columns. Multi-column indexes list several columns in one row. MySQL prefix lengths are written as `email(20)` |
| **Type** | BTREE, HASH, FULLTEXT, SPATIAL (MySQL), GIN, GIST, BRIN (PostgreSQL) |
| **Unique** | Whether the index enforces uniqueness |
| **Condition** | `WHERE` predicate for partial indexes (PostgreSQL) |
## Foreign keys tab
| Field | Description |
| --------------------------- | -------------------------------------------------------------- |
| **Columns** | Local column(s) |
| **Ref Table / Ref Columns** | Referenced table and column(s) |
| **Ref Schema** | Referenced schema, for cross-schema references |
| **On Delete / On Update** | Dropdowns: NO ACTION, RESTRICT, CASCADE, SET NULL, SET DEFAULT |
Right-click a foreign key and choose **Open \[table]** to jump to the referenced table. Right-click any row in these three grids for **Copy Name**, **Copy Definition**, **Copy As** (CSV, JSON, SQL), **Duplicate** (`Cmd+D`), and **Delete**. A row already marked for deletion offers **Undo Delete**.
## Saving changes
Nothing here reaches the server on its own. {what_0} queue on the tab, the toolbar counts them,
**Preview SQL** (`Cmd+Shift+P`) shows the statements they will produce, and `Cmd+S` runs them.
[Change Tracking](/features/change-tracking) covers the queue, undo (`Cmd+Z`) and redo (`Cmd+Shift+Z`). A save runs on the tab's own connection, database, and schema, the ones it was opened on, and never moves the sidebar or the toolbar.
* **Save Changes** (`Cmd+S` or the toolbar checkmark) applies the queue. Changes that can lose data, dropping a column, changing a type, adding NOT NULL, changing the primary key, first show a confirmation listing each one.
* **Preview SQL** (`Cmd+Shift+P`) shows the generated statements without executing them.
The queue outlives everything short of an explicit discard: closing the tab, closing the window, quitting, and **Refresh** all ask first. A save that never reaches the server leaves the tab open with its queue intact.
### When one statement fails
A save is often several statements, run in order. Engines with transactional DDL roll the whole set back; MySQL, MariaDB, and Oracle commit each one as it runs, so everything before the failure has landed while the queue still holds all of it. An **Error Applying Changes** sheet reports what the server said: refresh before saving again, or the second save replays work the server already did.
## Triggers tab
Lists **Name**, **Timing** (BEFORE, AFTER, INSTEAD OF), **Event** (INSERT, UPDATE, DELETE), and **Enabled** where the engine reports it. Select one to read its `CREATE TRIGGER` statement from the catalog, with **Copy** and **Open in Editor**. **New Trigger**, **Edit**, and **Delete** sit in the action bar; the editor opens the trigger's real DDL, including the trigger function on PostgreSQL.
Triggers are available for MySQL, MariaDB, PostgreSQL, SQLite, SQL Server, Oracle, libSQL, and Cloudflare D1; the tab is hidden elsewhere. Oracle does not return the trigger body, so the viewer and the editor start from the trigger header alone.
## DDL tab
Read-only `CREATE TABLE` with syntax highlighting and font size controls. **Copy**, **Export** as a `.sql` file, and **Open in Editor** send it onward. On PostgreSQL the `CREATE SEQUENCE` and `CREATE TYPE … AS ENUM` statements the table depends on are prepended, so the script runs on an empty database.
## Parts tab (ClickHouse)
Lists partitions and parts from `system.parts`. **Optimize** merges parts; **Drop Partition** and **Detach Partition** act on the selected partition. Detached data stays on disk and is unreadable until it is re-attached.
## Creating a new table
Choose **Database > New Table…**, or right-click empty space in the sidebar and choose **New Table…**. The tab holds a **Table Name** field (with Engine, Charset, and Collation pickers on MySQL and MariaDB), the same three editing grids, and a **SQL Preview** tab carrying the live `CREATE TABLE`. **Create Table** (`Cmd+Enter` or `Cmd+S`) executes it and opens the new table.
Visual table creation is supported for MySQL, MariaDB, PostgreSQL, PGlite, SQLite, SQL Server, ClickHouse, DuckDB, Oracle, Snowflake, libSQL, Cloudflare D1, Trino, Teradata, and Dameng.
## MongoDB collections
MongoDB structure is read-only, and inferred from the collection's first 200 documents: top-level field names are unioned across the sample, and each field takes its most common BSON type. `_id` comes first, marked as the primary key. The DDL tab shows indexes as `createIndex()` commands for `mongosh`, plus the validator and capped-collection options where present.
## Limitations
* **Changing a primary key on an existing table** works on MySQL, MariaDB, PostgreSQL, PGlite, SQL Server, DuckDB, Snowflake, and Dameng. Elsewhere the dropdown accepts the edit and the save produces nothing for it: rebuild the table by hand.
* **Check constraints and generated columns** have no field in the grid. Both show in the DDL tab; change them by running DDL yourself.
* **SQLite**: a column can be added, dropped, and renamed. No other column change generates SQL.
* **Cassandra / ScyllaDB**: add and drop column only, no index editing, no visual table creation.
* **Redshift, CockroachDB, BigQuery, Elasticsearch, SurrealDB, Beancount**: structure is read-only.
* **Redis, etcd, DynamoDB**: no table schema to edit.
## Refreshing
**Database > Refresh** (`Cmd+R`) or the toolbar refresh button reloads structure from the server; changes made through TablePro refresh on their own. A refresh reads the tab's own database and schema, not the sidebar's current selection.