Replace serial with GENERATED BY DEFAULT AS IDENTITY (#918)

## PR Info

<!-- mention the related issue -->
- Closes #688


## Breaking Changes

- [x] The query builder generates auto increment columns as GENERATED BY
DEFAULT AS IDENTITY instead of SERIAL in PostgreSQL

Author: Huliiiiii

CHANGELOG.md

@@ -59,6 +59,8 @@ assert_eq!(std::mem::size_of::<Value>(), 32);
 
 ### Breaking Changes
 
+* Replace `serial` with `GENERATED BY DEFAULT AS IDENTITY`
+
 * Removed inherent `SimpleExpr` methods that duplicate `ExprTrait`. If you encounter the following error, please add `use sea_query::ExprTrait` in scope https://github.com/SeaQL/sea-query/pull/890
 ```rust
 error[E0599]: no method named `like` found for enum `sea_query::Expr` in the current scope

src/backend/postgres/table.rs

@@ -242,12 +242,14 @@ impl TableBuilder for PostgresQueryBuilder {
 
 impl PostgresQueryBuilder {
     fn prepare_column_auto_increment(&self, column_type: &ColumnType, sql: &mut dyn SqlWriter) {
-        match &column_type {
-            ColumnType::SmallInteger => write!(sql, "smallserial").unwrap(),
-            ColumnType::Integer => write!(sql, "serial").unwrap(),
-            ColumnType::BigInteger => write!(sql, "bigserial").unwrap(),
+        let num_ty = match column_type {
+            ColumnType::SmallInteger => "SMALLINT",
+            ColumnType::Integer => "INTEGER",
+            ColumnType::BigInteger => "BIGINT",
             _ => unimplemented!("{:?} doesn't support auto increment", column_type),
-        }
+        };
+
+        write!(sql, "{num_ty} GENERATED BY DEFAULT AS IDENTITY").unwrap();
     }
 
     fn prepare_column_type_check_auto_increment(

src/lib.rs

@@ -565,7 +565,7 @@
 //!     table.to_string(PostgresQueryBuilder),
 //!     [
 //!         r#"CREATE TABLE IF NOT EXISTS "character" ("#,
-//!             r#""id" serial NOT NULL PRIMARY KEY,"#,
+//!             r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
 //!             r#""font_size" integer NOT NULL,"#,
 //!             r#""character" varchar NOT NULL,"#,
 //!             r#""size_w" integer NOT NULL,"#,

src/table/column.rs

@@ -671,7 +671,7 @@ impl ColumnDef {
     ///         .to_string(PostgresQueryBuilder),
     ///     [
     ///         r#"CREATE TABLE "glyph" ("#,
-    ///         r#""id" serial NOT NULL PRIMARY KEY,"#,
+    ///         r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
     ///         r#""tokens" ltree"#,
     ///         r#")"#,
     ///     ]

src/table/create.rs

@@ -52,7 +52,7 @@ use crate::{
 ///     table.to_string(PostgresQueryBuilder),
 ///     [
 ///         r#"CREATE TABLE IF NOT EXISTS "character" ("#,
-///             r#""id" serial NOT NULL PRIMARY KEY,"#,
+///             r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
 ///             r#""font_size" integer NOT NULL,"#,
 ///             r#""character" varchar NOT NULL,"#,
 ///             r#""size_w" integer NOT NULL,"#,
@@ -385,7 +385,7 @@ impl TableCreateStatement {
     ///     statement.to_string(PostgresQueryBuilder),
     ///     [
     ///         r#"CREATE TEMPORARY TABLE "font" ("#,
-    ///         r#""id" serial NOT NULL PRIMARY KEY,"#,
+    ///         r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
     ///         r#""name" varchar NOT NULL"#,
     ///         r#")"#,
     ///     ]

tests/postgres/table.rs

@@ -18,7 +18,7 @@ fn create_1() {
             .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TABLE "glyph" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""aspect" double precision NOT NULL,"#,
             r#""image" text"#,
             r#")"#,
@@ -45,7 +45,7 @@ fn create_2() {
             .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TABLE "font" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""name" varchar NOT NULL,"#,
             r#""variant" varchar(255) NOT NULL,"#,
             r#""language" varchar(255) NOT NULL"#,
@@ -88,7 +88,7 @@ fn create_3() {
             .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TABLE IF NOT EXISTS "character" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""font_size" integer NOT NULL,"#,
             r#""character" varchar(255) NOT NULL,"#,
             r#""size_w" integer NOT NULL,"#,
@@ -515,7 +515,7 @@ fn alter_10() {
             .to_string(PostgresQueryBuilder),
         [
             r#"ALTER TABLE "glyph""#,
-            r#"ADD COLUMN "aspect" serial NOT NULL UNIQUE PRIMARY KEY"#,
+            r#"ADD COLUMN "aspect" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL UNIQUE PRIMARY KEY"#,
         ]
         .join(" ")
     );
@@ -627,7 +627,7 @@ fn create_16() {
             .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TABLE "glyph" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""tokens" ltree"#,
             r#")"#,
         ]
@@ -661,7 +661,7 @@ fn create_17() {
         .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TABLE "font" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""name" varchar,"#,
             r#""variant" varchar(255) NOT NULL,"#,
             r#""language" varchar(255) NOT NULL,"#,
@@ -689,7 +689,7 @@ fn create_18() {
             .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TEMPORARY TABLE "font" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""name" varchar NOT NULL"#,
             r#")"#,
         ]
@@ -728,7 +728,7 @@ fn create_19() {
             .to_string(PostgresQueryBuilder),
         [
             r#"CREATE TABLE IF NOT EXISTS "character" ("#,
-            r#""id" serial NOT NULL PRIMARY KEY,"#,
+            r#""id" INTEGER GENERATED BY DEFAULT AS IDENTITY NOT NULL PRIMARY KEY,"#,
             r#""font_size" integer NOT NULL,"#,
             r#""character" varchar(255) NOT NULL,"#,
             r#""size_w" integer NOT NULL,"#,