比较两列，只选择一个用sql查询

Question

我有两列，让我们说col1和col2。它们都是float

总是if col1 = 0 then col2 > 0或col1 > 0 then col2 = 0

我只想选择一个大于零的列。

提前致谢

Answer 1

试试这个：

<ng-template #showInput>
        <div class="col-md-8 " [ngSwitch]="fieldInfo.dataTypeName">
                <input *ngSwitchCase="'Text'" class="form-control" [(ngModel)]="pageInfoBeans.nameValueMap[fieldInfo.name]" name="{{fieldInfo.name}}"
                        [required]="fieldInfo.requiredInd" [maxLength]="fieldInfo.fieldSize==0?5:fieldInfo.fieldSize" [disabled]="formEnableInd">

                <input *ngSwitchCase="'Email Address'" type="email" class="form-control" [(ngModel)]="pageInfoBeans.nameValueMap[fieldInfo.name]" name="{{fieldInfo.name}}"
                        [required]="fieldInfo.requiredInd" [maxLength]="fieldInfo.fieldSize==0?5:fieldInfo.fieldSize" [disabled]="formEnableInd"></ng-template>

Answer 2

其中一个总是零？

SELECT col1+col2

Answer 3

您也可以使用：

SELECT CASE WHEN Col1 > 0 THEN COL1 ELSE Col2 END from your_table

Answer 4

您可以将此用于linq

from t in Table
select new { Col = ( t.col1  > 0 )?t.col1 : t.col2  }