关于怎么查出数据库的值一系列的方法

从数据库中查询一系列数据的方法。

1.1 SQL语句

SELECT

express_price_id as expressPriceId,

express_id as expressId,

province_id as provinceId,

separate_weight as separateWeight,

first_heavy_price as firstHeavyPrice,

continued_heavy_price as continuedHeavyPrice,

status as status,

note as note,

update_time as updateTime,

update_user as updateUser

FROM express_price

WHERE express_price_id = #expressPriceId#

<sqlMap namespace="Common">

<select id="selectProvince"

resultClass="cn.agriculture.web.form.Item">

SELECT province_name as label,

province_id as value

FROM province

</select>

2. 2Java方法

a. 在controller中

@RequestMapping(value = "initEditExpressPrice", method = RequestMethod.GET)

public String initEditExpressPrice(Model model, ExpressPriceForm expressPriceForm) {

log.info("修改快递商所属价格初始化");

‍ List<Item> provinceList = itemListComponent.getProvinceList();

model.addAttribute("provinceList", provinceList); ‍

model.addAttribute("expressPriceForm", expressPriceService.searchExpressPrice(expressPriceForm));

return "manager/expressPrice/editExpressPrice";

}

b.在expressPriceForm.java (当然是要写在包中) 中

package cn.agriculture.web.form;

import javax.validation.constraints.Digits;

import cn.agriculture.common.validator.constraints.NotEmpty;
import lombok.Data;

@Data
public class ExpressPriceForm {

private String expressPriceId;
private String expressId;
private String provinceId;
private String provinceName;
@Digits(fraction = 2, integer = 10,message="{errors.separateWeight}")
@NotEmpty(field="分隔重量g",message="{errors.required}")
private String separateWeight;
@Digits(fraction = 2, integer = 10,message="{errors.firstHeavyPrice}")
@NotEmpty(field="首重费（元）",message="{errors.required}")
private String firstHeavyPrice;
@Digits(fraction = 2, integer = 10,message="{errors.continuedHeavyPrice}")
@NotEmpty(field="续重费（元）",message="{errors.required}")
private String continuedHeavyPrice;
private String status;
private String note;
private String updateTime;
private String updateUser;

}

c.(Service中)在searchExpressPrice方法中

Common.selectProvince

getProvinceList()

package cn.agriculture.web.service;

import java.util.List;

import jp.terasoluna.fw.dao.QueryDAO;
import jp.terasoluna.fw.dao.UpdateDAO;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import cn.agriculture.web.form.ExpressPriceForm;

@Service
public class ExpressPriceService {
@Autowired
QueryDAO queryDao;

@Autowired
UpdateDAO updateDao;
public ExpressPriceForm searchExpressPrice(ExpressPriceForm frm) {
ExpressPriceForm result = queryDao.executeForObject("ExpressPrice.selectExpressPrice               ", frm, ExpressPriceForm.class);
return result;
}

public List<Item> getProvinceList() {
return queryDao.executeForObjectList("Common.selectProvince", null);
}
｝

d.在manager/expressPrice/editExpressPrice.jsp 页面中

<form:select path="provinceId" itemValue="${expressPriceForm.provinceId}">

<form:options items="${provinceList}" itemLabel="label" itemValue="value" />

</form:select>

<form:input path="ProvinceName" value="${expressPriceForm.ProvinceName}" />

<div class="box-content">
<form:form modelAttribute="expressPriceForm" action="editExpressPrice" method="post">
<form:hidden path="expressId" value="${expressPriceForm.expressId}" />
<form:hidden path="expressPriceId" value="${expressPriceForm.expressPriceId}" /〉
<div class="alert alert-info">${message}<form:errors path="*"></form:errors></div>
<div class="controls">

<form:select path="provinceId" itemValue="${expressPriceForm.provinceId}">
<form:options items="${provinceList}" itemLabel="label" itemValue="value" />
</form:select>
<form:input path="ProvinceName"  value="${expressPriceForm.ProvinceName}" />
</div>
</form:form>

2.怎么用一个表的Id查询另一个表中的属性（两表关联）

2.1 SQL 语句如下所示

SELECT

express_price.express_price_id as expressPriceId,

express_price.express_id as expressId,

express_price.province_id as provinceId,

province.province_name as provinceName,

express_price.separate_weight as separateWeight,

express_price.first_heavy_price as firstHeavyPrice,

express_price.continued_heavy_price as continuedHeavyPrice,

express_price.status as status,

express_price.note as note,

express_price.update_time as updateTime,

express_price.update_user as updateUser

FROM express_price,province

WHERE

province.province_id=express_price.province_id

AND express_price_id = #expressPriceId#

2.2 Service controller Form都同上

在就jsp中用EL表达式显示

<div class="controls">

${expressPriceForm.provinceName}

</div>