SQL - 在包含数字和字母的列中搜索特定范围的最佳方法是什么？

Question

我有一个 table，代码中包含字母和数字，特别是 aa00 到 ZZ99。我无法确定在该列中搜索 dd01 - GG99 等范围的最佳方法。最好的方法是什么？（我在 RStudio 中使用 sqldf）

我试过使用 between 语句，但结果不是我想要的。事实上它显示的是相反的并且没有小写字母：

SELECT prodcode
  FROM data
 WHERE prodcat BETWEEN 'GG99' AND 'dd01';

评论编辑太长：

library(ggvis)
library(readr)
library(dplyr)
library(knitr)
library(sqldf)
library(tidyr)
data <- read_csv("C:/Users/name/Documents/test1.csv")
compn <-read_csv("C:/Users/name/Documents/test2.csv")


prodcode <- expand.grid(x1 = LETTERS,
                        x2 = letters,
                        x3 = 0:9,
                        x4 = 0:9)
prodcode$prodcat <- apply(data, 1, paste0, collapse = "")




test <- sqldf("SELECT prod
               FROM data, compn
               WHERE data.cono = compn.cono
               AND (SELECT * FROM prodcode 
                        WHERE (SUBSTR(UPPER(prodcat), 1, 2) >= 'DD' AND 
                        CAST(SUBSTR(prodcat, 3, 2) AS INT) >= 00 ) AND
                        (SUBSTR(UPPER(prodcat), 1, 2) <= 'GG' AND
                        CAST(SUBSTR(prodcat, 3, 2) AS INT) <= 99);
              GROUP BY prod
              ORDER BY prod ASC;")


test

Answer 1

这里是 SQL 代码，可以实现您的建议。在SQL中，需要将字母和数字分开进行比较。由于您的数字具有固定宽度，因此您可以不转换为 INT。如果您有非固定宽度的数值，则必须决定适当的排序行为是什么。

prodcode <- expand.grid(x1 = LETTERS,
                        x2 = letters,
                        x3 = 0:9,
                        x4 = 0:9)
prodcode$prodcat <- apply(prodcode, 1, paste0, collapse = "")

library(sqldf)

sqldf(
  "SELECT * FROM prodcode 
   WHERE (SUBSTR(UPPER(prodcat), 1, 2) >= 'DD' AND 
            CAST(SUBSTR(prodcat, 3, 2) AS INT) >= 00 ) AND
         (SUBSTR(UPPER(prodcat), 1, 2) <= 'GG' AND
            CAST(SUBSTR(prodcat, 3, 2) AS INT) <= 99)"
)

在子查询中使用

proddata <- data.frame(prodcode = c("DD15", "BB08", "FQ17", "NN11"),
                       value = rnorm(4, 100, 15))

prodcode <- expand.grid(x1 = LETTERS,
                        x2 = letters,
                        x3 = 0:9,
                        x4 = 0:9)
prodcode$prodcat <- apply(prodcode, 1, paste0, collapse = "")

library(sqldf)

sqldf(
  "SELECT * 
   FROM proddata
   WHERE prodcode IN (SELECT UPPER(prodcat) FROM prodcode 
                      WHERE (SUBSTR(UPPER(prodcat), 1, 2) >= 'DD' AND 
                      CAST(SUBSTR(prodcat, 3, 2) AS INT) >= 00 ) AND
                      (SUBSTR(UPPER(prodcat), 1, 2) <= 'GG' AND
                      CAST(SUBSTR(prodcat, 3, 2) AS INT) <= 99))"
)

Answer 2

您可能会考虑 grepl 和一个适当的伴随正则表达式公式，与 dplyr select 命令配对。如果无法查看 "test" 数据框实际包含的内容，目前很难为您提供帮助。（IE，没有可用的可重现示例）

SQL - 在包含数字和字母的列中搜索特定范围的最佳方法是什么？

SQL -What is the best way to search for a specific range in a column with numbers and letters?

mysql

r

sqldf

在子查询中使用