clean up table create/drop queries

This is more of a stylistic change, as no functional behavior differs,
however it makes diagnostics much easier and is theoretically faster
than the previous select code.

lib/dialects/mssql/query-generator.js

@@ -31,7 +31,7 @@ module.exports = (function() {
     },
     },
 
 
     createTableQuery: function(tableName, attributes, options) {
     createTableQuery: function(tableName, attributes, options) {
-      var query = "CREATE TABLE <%= tableName %> (<%= attributes%>)";
+      var query = "IF OBJECT_ID('[<%= escapedTable %>]', 'U') IS NULL CREATE TABLE <%= table %> (<%= attributes%>)";
       var attrStr     = []
       var attrStr     = []
         , self        = this
         , self        = this
         , primaryKeys = Utils._.keys(Utils._.pick(attributes, function(dataType){
         , primaryKeys = Utils._.keys(Utils._.pick(attributes, function(dataType){
@@ -44,12 +44,11 @@ module.exports = (function() {
       }
       }
 
 
       var values = {
       var values = {
-        unquotedTable: tableName,
-        tableName: this.quoteIdentifier(tableName.toString()),
+        escapedTable: this.quoteTable(tableName).replace(/"/g, ''),
+        table: this.quoteTable(tableName),
         attributes: attrStr.join(", ")
         attributes: attrStr.join(", ")
       };
       };
 
 
-      query = addTableExistsWrapper(query);
       return Utils._.template(query)(values).trim() + ";";
       return Utils._.template(query)(values).trim() + ";";
     },
     },
 
 
@@ -83,13 +82,12 @@ module.exports = (function() {
     },
     },
 
 
     dropTableQuery: function(tableName, options) {
     dropTableQuery: function(tableName, options) {
-      var query = "DROP TABLE <%= tableName %>";
+      var query = "IF OBJECT_ID('[<%= escapedTable %>]', 'U') IS NOT NULL DROP TABLE <%= table %>";
       var values = {
       var values = {
-        unquotedTable: tableName,
-        tableName: this.quoteIdentifier(tableName.toString())
+        escapedTable: this.quoteTable(tableName).replace(/"/g, ''),
+        table: this.quoteTable(tableName)
       };
       };
 
 
-      query = addTableExistsWrapper(query, true);
       return Utils._.template(query)(values).trim() + ";";
       return Utils._.template(query)(values).trim() + ";";
     },
     },
 
 
@@ -539,17 +537,6 @@ module.exports = (function() {
     return Utils.addTicks(identifier, "'");
     return Utils.addTicks(identifier, "'");
   }
   }
 
 
-  function addTableExistsWrapper(query, exists){
-    return [
-      'IF (',
-        (exists ? '' : 'NOT '), 'EXISTS (',
-        'SELECT * FROM INFORMATION_SCHEMA.TABLES',
-        " WHERE TABLE_NAME='<%= unquotedTable %>')",
-      ')',
-      ' BEGIN ', query, ' END'
-    ].join('');
-  }
-
   function mssqlDataTypeMapping(tableName, attr, dataType) {
   function mssqlDataTypeMapping(tableName, attr, dataType) {
     if (Utils._.includes(dataType, 'DATETIME')) {
     if (Utils._.includes(dataType, 'DATETIME')) {
       dataType = dataType.replace(/DATETIME/, 'DATETIME2');
       dataType = dataType.replace(/DATETIME/, 'DATETIME2');