Add english version of 16_join.md

content/trdsql/16_join.en.md

@@ -0,0 +1,86 @@
++++
+author = "Noboru Saito"
+title = "trdsql JOIN"
+date = "2024-04-11"
+description = "trdsql JOIN multiple files"
+weight = 16
+tags = [
+    "trdsql",
+    "SQL",
+	"JOIN",
+]
+categories = [
+    "trdsql",
+]
++++
+
+JOIN multiple files with trdsql
+
+Suppose you have the following two CSV files:
+
+abc.csv
+
+```CSV
+1,AAA
+2,BBB
+3,CCC
+```
+
+price.csv
+
+```CSV
+1,100
+2,500
+3,50
+```
+
+The following is the result of joining the two files:
+
+```CSV
+1,AAA,100
+2,BBB,500
+3,CCC,50
+```
+
+With trdsql, you can write SQL JOINs directly by using file names instead of tables.
+
+```console
+trdsql "SELECT a.c1, a.c2, p.c2" \
+         "FROM abc.csv AS a" \
+    "LEFT JOIN price.csv AS p" \
+               "USING (c1)"
+```
+
+For a 1-to-1 JOIN with the same number of corresponding columns, the result is the same as `INNER JOIN`.
+In the case of a LEFT JOIN, all rows of the specified abc.csv are displayed first, and price.csv is displayed only if there is a corresponding row.
+This time, since there is no header in the CSV, the column names are common c1, c2, etc., so the leftmost column (c1) is used as the common column for `USING`. This is the same as `ON a.c1 = p.c1`.
+
+When joining multiple CSV files, it is necessary to unify the presence or absence of headers.
+
+However, if the extension is automatically identifiable, it is possible to mix CSV and LTSV.
+
+unit.ltsv
+
+```LTSV
+id:1	unit:個
+id:2	unit:箱
+```
+
+Join the result of the previous CSV JOIN with LTSV.
+
+```console
+ trdsql -oat \
+       "SELECT a.c1, a.c2, p.c2, unit" \
+        " FROM abc.csv AS a" \
+    "LEFT JOIN price.csv AS p" \
+               "USING (c1)" \
+    "LEFT JOIN unit.ltsv AS u " \
+               "ON (a.c1 = u.id)"
++----+-----+-----+------+
+| c1 | c2  | c2  | unit |
++----+-----+-----+------+
+|  1 | AAA | 100 | 個   |
+|  2 | BBB | 500 | 箱   |
+|  3 | CCC |  50 |      |
++----+-----+-----+------+
+```

content/trdsql/16_join.md → content/trdsql/16_join.ja.md

@@ -19,13 +19,15 @@ categories = [
 以下の2つのCSVファイルがあったとして、
 
 abc.csv
+
 ```CSV
 1,AAA
 2,BBB
 3,CCC
 ```
 
 price.csv
+
 ```CSV
 1,100
 2,500
@@ -42,7 +44,7 @@ price.csv
 
 trdsqlではテーブルの代わりにファイル名を使用すれば、そのままSQLのJOINが書けます。
 
-```sh
+```console
 trdsql "SELECT a.c1, a.c2, p.c2" \
          "FROM abc.csv AS a" \
     "LEFT JOIN price.csv AS p" \
@@ -58,14 +60,15 @@ LEFT JOINの場合は、先に指定したabc.csvの行はすべて表示され
 しかしながら、自動判別可能な拡張子になっていれば、CSVとLTSV等の混在は可能です。
 
 unit.ltsv
+
 ```LTSV
 id:1	unit:個
 id:2	unit:箱
 ```
 
 先程のCSVのJOINの結果に更にLTSVをJOINします。
 
-```sh
+```console
  trdsql -oat \
        "SELECT a.c1, a.c2, p.c2, unit" \
         " FROM abc.csv AS a" \