How do I install the Modify Schema skill?

Run npx skillmds@latest add agents-store/modify-schema in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Modify Schema free to use?

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Who published Modify Schema?

agents-store (@agents-store) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Modify Schema by agents-store — Agent Skill

Name: Modify Schema
Author: agents-store

Modify Schema

This skill should be used when the user asks to "alter a table", "rename a column", "change column type", "drop a column", "drop a table", "remove a constraint", "delete a junction table", "add default value", "set NOT NULL", or needs to modify an existing PostgreSQL schema that is connected to NocoDB or NocoBase.

agents-store c51dc39 2 files · 5.1 KB Updated Sep 17, 2026

File contents

Modify Schema — ALTER TABLE & DROP Operations

How to safely modify PostgreSQL tables that are connected as external data sources to NocoDB and NocoBase.

Add Columns

-- Text
ALTER TABLE "public"."products" ADD "title" text;

-- Number
ALTER TABLE "public"."products" ADD "quantity" bigint;

-- Decimal
ALTER TABLE "public"."products" ADD "price" decimal(10, 2);

-- Percent
ALTER TABLE "public"."products" ADD "discount" double precision;

-- Rating
ALTER TABLE "public"."products" ADD "rating" smallint DEFAULT 0;

-- Boolean
ALTER TABLE "public"."products" ADD "is_active" bool DEFAULT false;

-- DateTime
ALTER TABLE "public"."products" ADD "published_at" timestamp;

-- DateTime with TZ
ALTER TABLE "public"."products" ADD "event_at" timestamptz;

-- Date only
ALTER TABLE "public"."products" ADD "birth_date" date;

-- Time only
ALTER TABLE "public"."products" ADD "start_time" time;

-- JSON
ALTER TABLE "public"."products" ADD "metadata" json;

-- FK column (type must match parent PK)
ALTER TABLE "public"."products" ADD "category_id" int4;

Rename Column

ALTER TABLE "public"."products" RENAME COLUMN "old_name" TO "new_name";

Change Column Type

ALTER TABLE "public"."products" ALTER COLUMN "price" DROP DEFAULT;
ALTER TABLE "public"."products" ALTER COLUMN "price" TYPE decimal(12, 4)
    USING "price"::decimal(12, 4);

Set / Remove DEFAULT

-- Set default
ALTER TABLE "public"."products" ALTER COLUMN "status" SET DEFAULT 'draft';

-- Remove default
ALTER TABLE "public"."products" ALTER COLUMN "status" DROP DEFAULT;

Set / Remove NOT NULL

-- Set NOT NULL
ALTER TABLE "public"."products" ALTER COLUMN "title" SET NOT NULL;

-- Remove NOT NULL
ALTER TABLE "public"."products" ALTER COLUMN "title" DROP NOT NULL;

Drop Column

ALTER TABLE "public"."products" DROP COLUMN "obsolete_field";

Drop Table

DROP TABLE IF EXISTS "public"."table_name";

Drop FK Constraint

When removing a relation, drop the constraint first, then the FK column:

-- 1. Drop FK constraint
ALTER TABLE "public"."child_table" DROP CONSTRAINT "fk_name";

-- 2. Drop FK column
ALTER TABLE "public"."child_table" DROP COLUMN "parent_id";

Drop Junction Table (Many-to-Many)

For M2M relations, drop FK constraints before the table:

-- 1. Drop FK constraints
ALTER TABLE "public"."nc_m2m_a_b" DROP CONSTRAINT "fk_name_1";
ALTER TABLE "public"."nc_m2m_a_b" DROP CONSTRAINT "fk_name_2";

-- 2. Drop table
DROP TABLE IF EXISTS "public"."nc_m2m_a_b";

Drop Index

DROP INDEX IF EXISTS "public"."idx_table_column";

Safe Modification Order

When making complex schema changes:

Drop dependent FK constraints first
Modify or drop columns
Add new columns
Add new FK constraints
Add indexes on new FK columns

---name: modify-schemadescription: This skill should be used when the user asks to "alter a table", "rename a column", "change column type", "drop a column", "drop a table", "remove a constraint", "delete a junction table", "add default value", "set NOT NULL", or needs to modify an existing PostgreSQL schema that is connected to NocoDB or NocoBase.---# Modify Schema — ALTER TABLE & DROP OperationsHow to safely modify PostgreSQL tables that are connected as external data sources to NocoDB and NocoBase.## Add Columns```sql-- TextALTER TABLE "public"."products" ADD "title" text;-- NumberALTER TABLE "public"."products" ADD "quantity" bigint;-- DecimalALTER TABLE "public"."products" ADD "price" decimal(10, 2);-- PercentALTER TABLE "public"."products" ADD "discount" double precision;-- RatingALTER TABLE "public"."products" ADD "rating" smallint DEFAULT 0;-- BooleanALTER TABLE "public"."products" ADD "is_active" bool DEFAULT false;-- DateTimeALTER TABLE "public"."products" ADD "published_at" timestamp;-- DateTime with TZALTER TABLE "public"."products" ADD "event_at" timestamptz;-- Date onlyALTER TABLE "public"."products" ADD "birth_date" date;-- Time onlyALTER TABLE "public"."products" ADD "start_time" time;-- JSONALTER TABLE "public"."products" ADD "metadata" json;-- FK column (type must match parent PK)ALTER TABLE "public"."products" ADD "category_id" int4;```## Rename Column```sqlALTER TABLE "public"."products" RENAME COLUMN "old_name" TO "new_name";```## Change Column Type```sqlALTER TABLE "public"."products" ALTER COLUMN "price" DROP DEFAULT;ALTER TABLE "public"."products" ALTER COLUMN "price" TYPE decimal(12, 4) USING "price"::decimal(12, 4);```## Set / Remove DEFAULT```sql-- Set defaultALTER TABLE "public"."products" ALTER COLUMN "status" SET DEFAULT 'draft';-- Remove defaultALTER TABLE "public"."products" ALTER COLUMN "status" DROP DEFAULT;```## Set / Remove NOT NULL```sql-- Set NOT NULLALTER TABLE "public"."products" ALTER COLUMN "title" SET NOT NULL;-- Remove NOT NULLALTER TABLE "public"."products" ALTER COLUMN "title" DROP NOT NULL;```## Drop Column```sqlALTER TABLE "public"."products" DROP COLUMN "obsolete_field";```## Drop Table```sqlDROP TABLE IF EXISTS "public"."table_name";```## Drop FK ConstraintWhen removing a relation, drop the constraint first, then the FK column:```sql-- 1. Drop FK constraintALTER TABLE "public"."child_table" DROP CONSTRAINT "fk_name";-- 2. Drop FK columnALTER TABLE "public"."child_table" DROP COLUMN "parent_id";```## Drop Junction Table (Many-to-Many)For M2M relations, drop FK constraints before the table:```sql-- 1. Drop FK constraintsALTER TABLE "public"."nc_m2m_a_b" DROP CONSTRAINT "fk_name_1";ALTER TABLE "public"."nc_m2m_a_b" DROP CONSTRAINT "fk_name_2";-- 2. Drop tableDROP TABLE IF EXISTS "public"."nc_m2m_a_b";```## Drop Index```sqlDROP INDEX IF EXISTS "public"."idx_table_column";```## Safe Modification OrderWhen making complex schema changes:1. Drop dependent FK constraints first2. Modify or drop columns3. Add new columns4. Add new FK constraints5. Add indexes on new FK columns

Frequently asked questions