feat: add categories

internal/db/migrations/00005_create_categories_tables.sql

@@ -0,0 +1,24 @@
+-- +goose Up
+-- +goose StatementBegin
+CREATE TABLE categories (
+    id TEXT NOT NULL PRIMARY KEY,
+    name TEXT NOT NULL,
+    description TEXT,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE TABLE transaction_categories (
+    category_id TEXT NOT NULL REFERENCES categories(id) ON DELETE CASCADE,
+    transaction_id TEXT NOT NULL REFERENCES transactions(id) ON DELETE CASCADE,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (category_id, transaction_id)
+);
+-- +goose StatementEnd
+
+-- +goose Down
+-- +goose StatementBegin
+DROP TABLE transaction_categories;
+DROP TABLE categories;
+-- +goose StatementEnd

internal/model/financial_management.go

@@ -40,3 +40,11 @@ type Tag struct {
 	CreatedAt time.Time `db:"created_at"`
 	UpdatedAt time.Time `db:"updated_at"`
 }
+
+type Category struct {
+	ID          string    `db:"id"`
+	Name        string    `db:"name"`
+	Description *string   `db:"description"`
+	CreatedAt   time.Time `db:"created_at"`
+	UpdatedAt   time.Time `db:"updated_at"`
+}