Question

我正在使用Microsoft SQL Server Management Studio 2008.

我有一个Blood_Pressure_Systolic字段和一个Blood_Pressure_Diastolic字段。我需要根据梅奥诊所的类别，使用这两个字段来识别正常血压，高血压前期，1期高血压和2期高血压：Mayo Clinic Blood Pressure Chart

我目前正在使用下面的CASE表达式来过滤每个类别的收缩压范围和舒张压范围。但是，如果一个人的收缩压在较低的范围内，而舒张血压在较高的范围内，我想要返回更高的范围，反之亦然。例如，如果约翰史密斯有125收缩期（高血压前期）和95舒张期（1期高血压），那么我希望该领域返回他有1期高血压。

CASE WHEN BP_Systolic < '120' AND BP_Diastolic < '80' THEN 'Normal'

WHEN BP_Systolic BETWEEN '120' AND '139' OR BP_Diastolic BETWEEN '80' AND '89' THEN 'Prehypertension'

WHEN BP_Systolic BETWEEN '140' AND '159' OR BP_Diastolic BETWEEN '90' AND '99' THEN 'Stage 1 Hypertension'

WHEN BP_Systolic >= '160' OR BP_Diastolic >= '100' THEN 'Stage 2 Hypertension'
END AS BP_Category

Answer 1

我认为只需对CASE子句进行排序就可以了，因为它是按顺序解析的：

CASE 
    WHEN BP_Systolic >= '160' OR BP_Diastolic >= '100' THEN 'Stage 2 Hypertension'
    WHEN BP_Systolic BETWEEN '140' AND '159' OR BP_Diastolic BETWEEN '90' AND '99' THEN 'Stage 1 Hypertension'
    WHEN BP_Systolic BETWEEN '120' AND '139' OR BP_Diastolic BETWEEN '80' AND '89' THEN 'Prehypertension'
    WHEN BP_Systolic < '120' AND BP_Diastolic < '80' THEN 'Normal'
END AS BP_Category

虚拟小提琴试试：http://sqlfiddle.com/#!3/8ad7f/3

Answer 2

case语句按顺序进行评估。因此，本声明优先考虑“正常”（虽然根据其定义，放置无关紧要）。要优先考虑其他事项，请颠倒顺序：

CASE WHEN BP_Systolic >= '160' OR BP_Diastolic >= '100'
     THEN 'Stage 2 Hypertension'
     WHEN BP_Systolic BETWEEN '140' AND '159' OR
           BP_Diastolic BETWEEN '90' AND '99'
     THEN 'Stage 1 Hypertension'
     WHEN BP_Systolic BETWEEN '120' AND '139' OR
          BP_Diastolic BETWEEN '80' AND '89'
     THEN 'Prehypertension'
     WHEN BP_Systolic < '120' AND BP_Diastolic < '80'
     THEN 'Normal'
END AS BP_Category

过滤高血压类别的血压，同时返回更高的类别

2 个答案: