feat: support drop constraint in pg

Author: taozhi8833998

pegjs/postgresql.pegjs

@@ -1890,6 +1890,7 @@ alter_action_list
 alter_action
   = ALTER_ADD_COLUMN
   / ALTER_ADD_CONSTRAINT
+  / ALTER_DROP_CONSTRAINT
   / ALTER_DROP_COLUMN
   / ALTER_ADD_INDEX_OR_KEY
   / ALTER_ADD_FULLETXT_SPARITAL_INDEX
@@ -1964,6 +1965,24 @@ ALTER_ADD_CONSTRAINT
       }
     }
 
+ALTER_DROP_CONSTRAINT
+  = KW_DROP __ kc:'CONSTRAINT'i __ c:ident {
+  /* => {
+        action: 'drop';
+        constraint: ident,
+        keyword: 'constraint',
+        resource: 'constraint',
+        type: 'alter';
+      } */
+      return {
+        action: 'drop',
+        constraint: c,
+        keyword: kc.toLowerCase(),
+        resource: 'constraint',
+        type: 'alter',
+      }
+    }
+
 ALTER_ADD_INDEX_OR_KEY
   = KW_ADD __
     id:create_index_definition

test/postgres.spec.js

@@ -1929,6 +1929,20 @@ describe('Postgres', () => {
         'SELECT * FROM "table_name" WHERE foo.bar.baz.qux = FALSE'
       ]
     },
+    {
+      title: 'drop constraint',
+      sql: [
+        `ALTER TABLE "test" DROP CONSTRAINT "test_constraint";`,
+        'ALTER TABLE "test" DROP CONSTRAINT "test_constraint"'
+      ]
+    },
+    {
+      title: 'add constraint',
+      sql: [
+        'ALTER TABLE "configuration" ADD CONSTRAINT "configuration_pk" PRIMARY KEY("something","something_else","something_something_else");',
+        'ALTER TABLE "configuration" ADD CONSTRAINT "configuration_pk" PRIMARY KEY ("something", "something_else", "something_something_else")',
+      ]
+    },
   ]
   function neatlyNestTestedSQL(sqlList){
     sqlList.forEach(sqlInfo => {