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Does the R function sqldf() support a way to show table columns similar to what the sql command "desc my_table" would do. It does not seem to support "desc my_table" or "describe my_table" and I'm not seeing a way to do this in the documentation at the links below:

https://www.rdocumentation.org/packages/sqldf/versions/0.4-11

https://www.rdocumentation.org/packages/sqldf/versions/0.4-11/topics/sqldf

install.packages("sqldf") > data_file <- "path/to/file/dash-activity.csv" > data <- read.csv(data_file) > sqldf(" + select + state, + count(*) as count, + round(cast(count(*) as real)/154 * 100, 2) as pct + from data + group by 1 + order by 1 + ") state count pct 1 DE 12 7.79 2 FL 18 11.69 3 HI 23 14.94 4 KY 5 3.25 5 MD 31 20.13 6 ME 4 2.60 7 NC 7 4.55 8 ND 4 2.60 9 NM 13 8.44 10 NV 4 2.60 11 RI 5 3.25 12 VA 9 5.84 13 VT 13 8.44 14 WV 6 3.90 > sqldf(" + desc data + ") Error: near "desc": syntax error > sqldf(" + describe data + ") Error: near "describe": syntax error >

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The accepted answer gives the following results (my table is named "data")

> sqldf("pragma table_info('data')") cid name type notnull dflt_value pk 1 0 sex TEXT 0 NA 0 2 1 race TEXT 0 NA 0 3 2 grade TEXT 0 NA 0 4 3 location_id INTEGER 0 NA 0 5 4 state TEXT 0 NA 0 6 5 location_desc TEXT 0 NA 0 7 6 short_question TEXT 0 NA 0 8 7 greater_risk_question TEXT 0 NA 0 9 8 pct_were_not_active REAL 0 NA 0 10 9 units TEXT 0 NA 0
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  • I think sqldf uses sqlite by default, so you need to find whatever is equivalent to desc in sqlite. The package is just a front-end to whatever type of database you're using. Commented Nov 8, 2022 at 21:39
  • 1
    Maybe relevant - stackoverflow.com/questions/3330435/… Commented Nov 8, 2022 at 21:42
  • This is FAQ#9 on the sqldf github home page: github.com/ggrothendieck/sqldf Commented Nov 9, 2022 at 9:31
  • The link seems to not go anywhere. Commented Nov 11, 2022 at 1:47
  • @John, Don't know who you are responding to but both the links in the comments work fine for me. Commented Nov 13, 2022 at 17:28

1 Answer 1

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Using pragma:

library(sqldf) d <- head(iris[ c(1,5) ]) sqldf("select * from d") sqldf("pragma table_info('d')") # cid name type notnull dflt_value pk # 1 0 Sepal.Length REAL 0 NA 0 # 2 1 Species TEXT 0 NA 0

See SQLite Describe Table.

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