解决PagerUtils.limit 不支持PostgreSQL的bug

参考MySQL的Limit实现，增加PGLimit实现PagerUtils.limit 支持生成PostgreSQL的分页查询sql语句

src/test/java/com/alibaba/druid/postgresql/PGLimitTest.java

@@ -0,0 +1,27 @@
+package com.alibaba.druid.postgresql;
+
+import com.alibaba.druid.util.JdbcConstants;
+
+/**
+ * 
+ * @author lizongbo
+ * 
+ */
+public class PGLimitTest {
+
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		String dbType = JdbcConstants.POSTGRESQL;// "postgresql";
+		// dbType = "mysql";
+		String sql = " select * from brandinfo where 1=1 and brandid > 100 order by brandid asc";
+		String sqlLimit = com.alibaba.druid.sql.PagerUtils.limit(sql, dbType,
+				2499, 100);
+		System.out.println("sqlLimit == " + sqlLimit);
+		String sqlCount = com.alibaba.druid.sql.PagerUtils.count(sql, dbType);
+		System.out.println("sqlCount == " + sqlCount);
+
+	}
+
+}