更新：
是的，就是这样！
就像 mloskot 说的那样，整个表都需要被倾倒。使用 sql 选择字段会丢失有关字段宽度的信息。
谢谢，解决了！
大家好，
我对ogr2ogr有疑问。我正在尝试将 PostgreSQL 表格转储到 Shapefile。ogr2ogr 似乎改变了整数和字符等数据类型的大小。
这是 Shapefile 集被读入的 DB 结构的一部分：
Table "test"
nd_1 - numeric(8,0)
nd_2 - numeric(2,0)
nd_3 - numeric(2,0)
nd_9 - character varying(60)
它看起来正确。
乐趣从这里开始：
ogr2ogr air5000.shp "PG: [...]" sql 'select
CAST(nd_1 AS INTEGER),
CAST(nd_2 AS INTEGER),
CAST(nd_3 as INTEGER),
CAST(ND_9 AS CHARACTER VARYING(60))
from test' ;
然后
dbview -e test.dbf
Field Name Type Length Decimal Pos
nd 1 - N - 11 - 0
nd 2 - N - 11 - 0
nd 3 - N - 11 - 0
nd 9 - C - 80 - 0
num-length 从8,2,2变为11， char 长度从10变为80。
我读到如果未指定宽度（长度），这些是默认值。
如何指定宽度？
我尝试了有或没有施法的每一个组合，如下所示：
select
CAST(nd_1 AS NUMERIC),
CAST(nd_2 AS NUMERIC),
CAST(nd_3 as NUMERIC),
CAST(ND_9 AS CHARACTER VARYING(60))
这给出了dbview：
Field Name Type Length Decimal Pos
nd 1 - N - 24 - 15
nd 2 - N - 24 - 15
nd 3 - N - 24 - 15
nd 9 - C - 80 - 0
没有强制转换 ( select * from test) 给出
Field Name Type Length Decimal Pos
nd 1 - N - 24 - 15
nd 2 - N - 24 - 15
nd 3 - N - 24 - 15
nd 9 - C - 80 - 0
在任何情况下都与原件相去甚远。
debugfile [--debug on]恕我直言，没有什么特别的，这是我试过的 3 ogr2ogr 命令的输出：
PG: PQexec(DECLARE executeSQLCursor CURSOR for select CAST(nd_1 AS INTEGER), CAST(nd_2 AS INTEGER), CAST(nd_3 as INTEGER), CAST(ND_9 AS CHARACTER VARYING(60)) from test)
PG: PQexec(DECLARE OGRPGResultLayerReader CURSOR for select CAST(nd_1 AS INTEGER), CAST(nd_2 AS INTEGER), CAST(nd_3 as INTEGER), CAST(ND_9 AS CHARACTER VARYING(60)) from test)
PG: PQexec(DECLARE OGRPGResultLayerReader CURSOR for select CAST(nd_1 AS INTEGER), CAST(nd_2 AS INTEGER), CAST(nd_3 as INTEGER), CAST(ND_9 AS CHARACTER VARYING(60)) from test)
PG: 2 features read on layer 'sql_statement'.
PG: PQexec(DECLARE executeSQLCursor CURSOR for select CAST(nd_1 AS NUMERIC), CAST(nd_2 AS NUMERIC), CAST(nd_3 as NUMERIC), CAST(ND_9 AS CHARACTER VARYING(60)) from test)
PG: PQexec(DECLARE OGRPGResultLayerReader CURSOR for select CAST(nd_1 AS NUMERIC), CAST(nd_2 AS NUMERIC), CAST(nd_3 as NUMERIC), CAST(ND_9 AS CHARACTER VARYING(60)) from test)
PG: PQexec(DECLARE OGRPGResultLayerReader CURSOR for select CAST(nd_1 AS NUMERIC), CAST(nd_2 AS NUMERIC), CAST(nd_3 as NUMERIC), CAST(ND_9 AS CHARACTER VARYING(60)) from test)
PG: 2 features read on layer 'sql_statement'.
PG: PQexec(DECLARE executeSQLCursor CURSOR for select * from test)
PG: PQexec(DECLARE OGRPGResultLayerReader CURSOR for select * from test)
PG: PQexec(DECLARE OGRPGResultLayerReader CURSOR for select * from test)
PG: 2 features read on layer 'sql_statement'.
我也尝试过-dsco precision=no，但这也无济于事。
也许dbview是在拉我的腿，但它正确显示了 Shapefile 设置的源 .dbf 的标题。
有人有什么想法吗？
EJ
更新： 你好mloskot，
感谢您的回复和重新格式化，非常感谢！
我在 GDAL 1.6.3 上。
我尝试指定宽度，但没有任何区别。
ogr2ogr test.shp "PG: [...] " -sql 'select CAST(nd_1 AS INTEGER), CAST(nd_2 AS numeric(2,0)), CAST(nd_3 as NUMERIC(2,0)) from test' ;
给出：
Field Name Type Length Decimal Pos
nd 1 N 11 0
nd 2 N 24 15
nd 3 N 24 15
是的，我尝试在不强制转换的情况下指定字段，如下所示：
ogr2ogr air5000.shp "PG: [...] "-sql 'select nd_1, nd_2, nd_3, ND_9 from test'
这使：
Field Name Type Length Decimal Pos
nd 1 N 24 15
nd 2 N 24 15
nd 3 N 24 15
nd 9 C 80 0
试
integer(field_length)
像
CAST(nd_2 AS INTEGER(2))
不起作用，给出错误
ERROR 1: ERROR: current transaction is aborted, commands ignored until end of transaction block
也许我的 Postgresql 和 PostGIS 版本过时了？Postgres = 8.3.5，PostGIS = 1.3.3
我会检查 Shapelib，我刚刚安装了它。