Merge PR #410: Add support for @@variables in MariaDB-like databases

Author: nene

src/languages/mariadb/mariadb.formatter.ts

@@ -274,7 +274,7 @@ export default class MariaDbFormatter extends Formatter {
       identTypes: ['``'],
       identChars: { first: '$', rest: '$', allowFirstCharNumber: true },
       variableTypes: [
-        { regex: '@[A-Za-z0-9_.$]+' },
+        { regex: '@@?[A-Za-z0-9_.$]+' },
         { quote: '""', prefixes: ['@'], requirePrefix: true },
         { quote: "''", prefixes: ['@'], requirePrefix: true },
         { quote: '``', prefixes: ['@'], requirePrefix: true },

src/languages/mysql/mysql.formatter.ts

@@ -243,7 +243,7 @@ export default class MySqlFormatter extends Formatter {
       identTypes: ['``'],
       identChars: { first: '$', rest: '$', allowFirstCharNumber: true },
       variableTypes: [
-        { regex: '@[A-Za-z0-9_.$]+' },
+        { regex: '@@?[A-Za-z0-9_.$]+' },
         { quote: '""', prefixes: ['@'], requirePrefix: true },
         { quote: "''", prefixes: ['@'], requirePrefix: true },
         { quote: '``', prefixes: ['@'], requirePrefix: true },

src/languages/singlestoredb/singlestoredb.formatter.ts

@@ -242,7 +242,7 @@ export default class SingleStoreDbFormatter extends Formatter {
       identTypes: ['``'],
       identChars: { first: '$', rest: '$', allowFirstCharNumber: true },
       variableTypes: [
-        { regex: '@[A-Za-z0-9_$]+' },
+        { regex: '@@?[A-Za-z0-9_$]+' },
         { quote: '``', prefixes: ['@'], requirePrefix: true },
       ],
       lineCommentTypes: ['--', '#'],

test/behavesLikeMariaDbFormatter.ts

@@ -89,6 +89,18 @@ export default function behavesLikeMariaDbFormatter(format: FormatFn) {
     `);
   });
 
+  it('supports @@ system variables', () => {
+    const result = format('SELECT @@GLOBAL.time, @@SYSTEM.date, @@hour FROM foo;');
+    expect(result).toBe(dedent`
+      SELECT
+        @@GLOBAL.time,
+        @@SYSTEM.date,
+        @@hour
+      FROM
+        foo;
+    `);
+  });
+
   // Issue #181
   it('does not wrap CHARACTER SET to multiple lines', () => {
     expect(format('ALTER TABLE t MODIFY col1 VARCHAR(50) CHARACTER SET greek')).toBe(dedent`

test/mysql.test.ts

@@ -53,19 +53,6 @@ describe('MySqlFormatter', () => {
     `);
   });
 
-  // TODO: disabled for now
-  it.skip('supports @@ system variables', () => {
-    const result = format('SELECT @@GLOBAL.time, @@SYSTEM.date, @@hour FROM foo;');
-    expect(result).toBe(dedent`
-      SELECT
-        @@GLOBAL.time,
-        @@SYSTEM.date,
-        @@hour
-      FROM
-        foo;
-    `);
-  });
-
   it('formats ALTER TABLE ... ALTER COLUMN', () => {
     expect(
       format(