1.使用自定义函数封装数据操作：
如：封装性别，查询性别时只需传入性别参数：select get_sex('1');
创建自定义函数SQL如下：
DELIMITER $$
USE `cn`$$
DROP FUNCTION IF EXISTS `get_sex`$$
CREATE DEFINER=`root`@`localhost` FUNCTION `get_sex`(sex VARCHAR(2)) RETURNS VARCHAR(2) CHARSET utf8
BEGIN
DECLARE return_str VARCHAR(2) DEFAULT '';
IF (sex='1') THEN
SET return_str = '男';
ELSEIF (sex='2') THEN
SET return_str = '女';
ELSE
SET return_str = '';
END IF;
RETURN return_str;
END$$
DELIMITER ;
=================================================================================================
2.调用mysql自带的函数格式化输出参数：
如：格式化输出日期时间：
select DATE_FORMAT(create_date,'%y-%m-%d %H:%i') AS create_date from t_user
根据字段值做判断并格式化输出：
SELECT
IFNULL(money,'0.00') AS money,
CASE WHEN STATUS = '1'
THEN '待处理'
WHEN STATUS = '2'
THEN '审核拒绝'
WHEN STATUS = '3'
THEN '处理中'
ELSE '转账成功'
END AS remark,
DATE_FORMAT(create_date,'%Y-%m-%d %T') AS date,
transfer_type
FROM t_user
==============================================================================================
3.合并查询结果并插入的SQL:
INSERT INTO t_doctor_money_apply (
user_id,
money,
`name`,
)
SELECT
user_id,
balance as money,
`name`,
FROM t_user
WHERE user_id = 1 limit 1
===========================================================================================
4.字段值算术SQL：
UPDATE t_user SET read_num = read_num + 1
===========================================================================================
5.mybatis中传参数：
表结构字段用$，如：${tableName},${field}
字符类型参数用#,如：#{userName}
整型参数用$,如: ${offset}
===========================================================================================
6.数据类型转换：
select cast(user_id as char) as user_id,
user_name,
user_type,
cast(friend_id as char) as friend_id
from t_user
===========================================================================================
7.使用自定义存储过程：
如：mybatis调用存储过程并传递参数：
{call t_user_procedure(?,?,?,?,?,?)}
===========================================================================================
8.left join on: 左边是主表，右边是附表，on是连接点，where接条件
SELECT (
(SELECT COUNT(1)
FROM t_patient_follow_consult AS t1
LEFT JOIN t_disease AS t2
ON t2.`disease_id`=t1.`disease_id`
WHERE t1.`patient_id`=#{patient_id} AND t1.`doctor_id`=#{doctor_id})
) AS count
==================================================================================
9.数据库操作：
获取数据库的所有表名：
SELECT table_name FROM information_schema.tables WHERE table_schema=#{db}
获取表的所有字段：
SHOW COLUMNS FROM ${table}
=================================================================================
10.当天新记录：
create_date > DATE_FORMAT(NOW(),'%Y-%m-%d 00:00:00')
当月新记录：
create_date > DATE_SUB(TIMESTAMP(DATE(SYSDATE())),INTERVAL DAYOFMONTH(TIMESTAMP(DATE(SYSDATE())))-1 DAY)
=================================================================================
11.按中文名的首字母排序
ORDER BY CONVERT(username USING gbk) COLLATE gbk_chinese_ci ASC
=====================================================================================
12.mysql全文检索
当检索英文时，直接检索。
当检索中文时：将中文转成unicode存储，检索时，把关键字转为unicode搜索。
如：key='俊',转成unicode为：u4FCA ,搜索的字段名为n=unicode_name,则:
SELECT * FROM `user` WHERE MATCH(unicode_name)AGAINST('u4FCA' IN NATURAL LANGUAGE MODE);
中文转unicode工具类：
package fullText;
import java.io.UnsupportedEncodingException;
public class UnicodeConverter {
public static void main(String[] args) throws UnsupportedEncodingException {
String s = "java工程师";
s = toEncodedUnicode(s, false);
System.out.println("to unicode:\t\t" + s);
System.out.println("from unicode : " + fromEncodedUnicode(s.toCharArray(), 0, s.length()));
}
private static final char[] hexDigit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
'F' };
private static char toHex(int nibble) {
return hexDigit[(nibble & 0xF)];
}
public static String toEncodedUnicode(String theString, boolean escapeSpace) {
int len = theString.length();
int bufLen = len * 2;
if (bufLen < 0) {
bufLen = Integer.MAX_VALUE;
}
StringBuffer outBuffer = new StringBuffer(bufLen);
for (int x = 0; x < len; x++) {
char aChar = theString.charAt(x);
if ((aChar > 61) && (aChar < 127)) {
if (aChar == '\\') {
outBuffer.append('\\');
outBuffer.append('\\');
continue;
}
outBuffer.append(aChar);
continue;
}
switch (aChar) {
case ' ':
if (x == 0 || escapeSpace)
outBuffer.append('\\');
outBuffer.append(' ');
break;
case '\t':
outBuffer.append('\\');
outBuffer.append('t');
break;
case '\n':
outBuffer.append('\\');
outBuffer.append('n');
break;
case '\r':
outBuffer.append('\\');
outBuffer.append('r');
break;
case '\f':
outBuffer.append('\\');
outBuffer.append('f');
break;
case '=': // Fall through
case ':': // Fall through
case '#': // Fall through
case '!':
outBuffer.append('\\');
outBuffer.append(aChar);
break;
default:
if ((aChar < 0x0020) || (aChar > 0x007e)) {
outBuffer.append('\\');
outBuffer.append('u');
outBuffer.append(toHex((aChar >> 12) & 0xF));
outBuffer.append(toHex((aChar >> 8) & 0xF));
outBuffer.append(toHex((aChar >> 4) & 0xF));
outBuffer.append(toHex(aChar & 0xF));
outBuffer.append(' ');
} else {
outBuffer.append(aChar);
}
}
}
return outBuffer.toString();
}
public static String fromEncodedUnicode(String str) {
return fromEncodedUnicode(str.toCharArray(), 0, str.length());
}
public static String fromEncodedUnicode(char[] in, int off, int len) {
char aChar;
char[] out = new char[len]; // 只短不长
int outLen = 0;
int end = off + len;
while (off < end) {
aChar = in[off++];
if (aChar == '\\') {
aChar = in[off++];
if (aChar == 'u') {
// Read the xxxx
int value = 0;
for (int i = 0; i < 4; i++) {
aChar = in[off++];
switch (aChar) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
value = (value << 4) + aChar - '0';
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
value = (value << 4) + 10 + aChar - 'a';
break;
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
value = (value << 4) + 10 + aChar - 'A';
break;
default:
throw new IllegalArgumentException("Malformed \\uxxxx encoding.");
}
}
out[outLen++] = (char) value;
} else {
if (aChar == 't') {
aChar = '\t';
} else if (aChar == 'r') {
aChar = '\r';
} else if (aChar == 'n') {
aChar = '\n';
} else if (aChar == 'f') {
aChar = '\f';
}
out[outLen++] = aChar;
}
} else {
out[outLen++] = aChar;
}
}
return new String(out, 0, outLen);
}
}
====================================================================================
13.计算地球表面两点距离(开发附近的XX，距离，单位km)
两点坐标：A(latA,lonA) B(latB,lonB)
距离为：
SELECT 12733.129728*ASIN(SQRT(POWER(SIN((latA-latB)*PI()/360),2)+COS(latA*PI()/180)*COS(latB*PI()/180)*POWER(SIN((lonA-lonB)*PI()/360),2))) AS dist
如：A(40,113.55) B(42,113.21)
SELECT 12733.129728*ASIN(SQRT(POWER(SIN((40-42)*PI()/360),2)+COS(40*PI()/180)*COS(42*PI()/180)*POWER(SIN((113.55-113.21)*PI()/360),2))) AS dist
=======================================================================================
14. mybatis调用存储过程,例如:
<update id="doctorapplymoney" parameterMap="applyMoneyMap"
statementType="CALLABLE" >
{call doctor_applymoney_procedure(?,?,?,?,?,?,?,?,?)}
</update>
=======================================================================================
15.
