select name from tab_stu as s left join tab_yxmes as y on s.yxid=y.id where yxmc='计算机系'
#查出 韩顺平所在的院系信息
select yxmc from tab_stu as s left join tab_yxmes as y on s.yxid=y.id where name='韩顺平'
#3)查出在“行政楼”办公的院系名称。
select yxmc from tab_yxmes where xbdz like "行政楼%";
#4)查出男生女生各多少人。
select sex, count(*) from tab_stu group by sex
#5)查出人数最多的院系信息。
select y.yxmc as c from tab_stu as s left join tab_yxmes as y on s.yxid=y.id GROUP BY s.yxid order by c desc limit 1
#查出跟“罗弟华”同籍贯的所有人
select name from tab_stu where jg=(select jg from tab_stu where name='罗第华')
#8)查出有“河北”人就读的院系信息
select jg as '籍贯',yxmc as '院系名称' from tab_stu as s left join tab_yxmes as y on s.yxid=y.id where jg='河北'
#查出人数最多的院系的男女生各多少人。
select sex, count(*) as 人数 from tab_stu where yxid = (select yxid from tab_stu group by yxid order by count(*) desc limit 0,1) group by sex
#9)查出跟“河北女生”同院系的所有学生的信息。
select name from tab_stu where yxid=(select yxid from tab_stu where sex='女' and jg='河北')
.sql文件
/*
Navicat Premium Data Transfer
Source Server : myconnct
Source Server Type : MySQL
Source Server Version : 50617
Source Host : localhost:3306
Source Schema : db_0604
Target Server Type : MySQL
Target Server Version : 50617
File Encoding : 65001
Date: 04/06/2018 15:15:13
*/
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for tab_stu
-- ----------------------------
DROP TABLE IF EXISTS `tab_stu`;
CREATE TABLE `tab_stu` (
`id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`name` varchar(40) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`sex` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`jg` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`yxid` int(11) DEFAULT NULL,
PRIMARY KEY (`id`) USING BTREE,
INDEX `yxid`(`yxid`) USING BTREE,
CONSTRAINT `tab_stu_ibfk_1` FOREIGN KEY (`yxid`) REFERENCES `tab_yxmes` (`id`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB AUTO_INCREMENT = 7 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;
-- ----------------------------
-- Records of tab_stu
-- ----------------------------
INSERT INTO `tab_stu` VALUES (1, '罗第华', '男', '江西', 1);
INSERT INTO `tab_stu` VALUES (2, '韩顺平', '男', '四川', 2);
INSERT INTO `tab_stu` VALUES (3, '吴英累', '男', '黑龙江', 1);
INSERT INTO `tab_stu` VALUES (4, '王玉虹', '女', '河北', 3);
INSERT INTO `tab_stu` VALUES (5, '赵玉川', '男', '河北', 3);
INSERT INTO `tab_stu` VALUES (6, '刘招英', '女', '江西', 1);
-- ----------------------------
-- Table structure for tab_yxmes
-- ----------------------------
DROP TABLE IF EXISTS `tab_yxmes`;
CREATE TABLE `tab_yxmes` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`yxmc` varchar(40) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '院系名称',
`xbdz` varchar(40) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '系办地址',
`xbdh` varchar(40) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '系办电话',
PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;
-- ----------------------------
-- Records of tab_yxmes
-- ----------------------------
INSERT INTO `tab_yxmes` VALUES (1, '计算机系', '行政楼302', '01066886688');
INSERT INTO `tab_yxmes` VALUES (2, '数学系', '科研楼108', '010802820080');
INSERT INTO `tab_yxmes` VALUES (3, '物理系', '行政楼305', '0106768677');
SET FOREIGN_KEY_CHECKS = 1;