ColumnTypes() improvement.

[nicetip]

it was impossible to extract column types with Rows.ColumnTypes() function. but Crate's JSON response already contains column type information(col_types). this commit contains implement col_types. Look for following example codes.

Example Code:

package main

import ( "fmt" "database/sql" _ "go-crate" )

func main() { db, _ := sql.Open("crate", "http://127.0.0.1:4200") rows, _ := db.Query("select col1, col2 from tbl") types, _ := rows.ColumnTypes() for i, l := 0, len(types); i < l; i++ { t := types[i] fmt.Println(t.Name(), ":", t.DatabaseTypeName()) } }

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Ebert has finished reviewing this Pull Request and has found:

• 2 possible new issues (including those that may have been commented here).

You can see more details about this review at https://ebertapp.io/github/herenow/go-crate/pulls/22.