我正在将数据访问层从 Telerik ORM（已弃用）转换为 EF 6。它连接到 Oracle 12c 数据源，字符数限制为 30 个。有些表名和列名正好是 30 个字符（如下例所示），有些更短。
Linq to Sql 查询已经存在，并且可以使用 Telerik 进行查找，因为它使用列名的别名，如 t1、t2 等。而 EF 显然将原始列名复制为别名。在大多数情况下，除了代码表连接之外，这都有效，其中代码表的 PK 和父表的 FK 完全相同，然后它将 1 附加到列 alais 的末尾，从而使其成为 31 个字符。你可以猜到 Oracle 抱怨了。
我需要找到一种方法来强制 EF 使用更短的别名，有什么方法可以做到这一点吗？
这是 Linq 查询：
var dbElevationsHistory = (from elevationHist in dbContext.ElevationDataReadingJournals
join it in dbContext.MeasurementIssueTypes on elevationHist.MeasurementIssueTypeId equals it.MeasurementIssueTypeId into iType
from issueType in iType.DefaultIfEmpty()
join mt in dbContext.ElevationMeasureMethodTypes on elevationHist.ElevationMeasureMethodTypeId equals mt.ElevationMeasureMethodTypeId into mType
from methodType in mType.DefaultIfEmpty()
join at in dbContext.ElevationAccuracyTypes on elevationHist.ElevationAccuracyTypeId equals at.ElevationAccuracyTypeId into aType
from accuracyType in aType.DefaultIfEmpty()
join cAgency in dbContext.Organizations on elevationHist.CoopAgencyOrganizationId equals cAgency.OrganizationId into foundAgencies
from coopAgency in foundAgencies.DefaultIfEmpty()
where elevationHist.StationId == wellKey
select new { elevationHist, issueType, accuracyType, methodType, coopAgency })
.OrderByDescending(eh => eh.elevationHist.ModifiedDate)
.OrderByDescending(eh => eh.elevationHist.ElevationDataReadingJournalId);
以及它生成的sql查询：
SELECT
"Project1"."C1" AS "C1",
"Project1"."EWM_ELEVATION_DATA_READ_JRL_ID" AS "EWM_ELEVATION_DATA_READ_JRL_ID",
"Project1"."EWM_ELEVATION_DATA_READING_ID" AS "EWM_ELEVATION_DATA_READING_ID",
"Project1"."CRUD_TYPE" AS "CRUD_TYPE",
"Project1"."CRUD_DT" AS "CRUD_DT",
"Project1"."MEASUREMENT_DT" AS "MEASUREMENT_DT",
"Project1"."ORG_ID" AS "ORG_ID",
"Project1"."EWM_MEASUREMENT_ISSUE_TYPE_ID" AS "EWM_MEASUREMENT_ISSUE_TYPE_ID",
"Project1"."EWM_STATION_ID" AS "EWM_STATION_ID",
"Project1"."EWM_ELEV_MEASURE_METHOD_TYP_ID" AS "EWM_ELEV_MEASURE_METHOD_TYP_ID",
"Project1"."EWM_ELEVATION_ACCURACY_TYPE_ID" AS "EWM_ELEVATION_ACCURACY_TYPE_ID",
"Project1"."REFERENCE_POINT_ELEVATION" AS "REFERENCE_POINT_ELEVATION",
"Project1"."GROUND_SURFACE_ELEVATION" AS "GROUND_SURFACE_ELEVATION",
"Project1"."WATER_SURFACE_READING" AS "WATER_SURFACE_READING",
"Project1"."REFERENCE_POINT_READING" AS "REFERENCE_POINT_READING",
"Project1"."MANDATORY_READING" AS "MANDATORY_READING",
"Project1"."COMMENTS" AS "COMMENTS",
"Project1"."MODIFIED_DATE" AS "MODIFIED_DATE",
"Project1"."MODIFIED_USER" AS "MODIFIED_USER",
"Project1"."MODIFIED_PROC" AS "MODIFIED_PROC",
"Project1"."COOPERATING_AGENCY_ORG_ID" AS "COOPERATING_AGENCY_ORG_ID",
"Project1"."APPL_ID" AS "APPL_ID",
"Project1"."SUBMISSION_DATE" AS "SUBMISSION_DATE",
"Project1"."EWM_MEASUREMENT_ISSUE_TYPE_ID1" AS "EWM_MEASUREMENT_ISSUE_TYPE_ID1",
"Project1"."EWM_MEASURE_ISSUE_TYPE_CODE" AS "EWM_MEASURE_ISSUE_TYPE_CODE",
"Project1"."EWM_MEASURE_ISSUE_TYPE_DESC" AS "EWM_MEASURE_ISSUE_TYPE_DESC",
"Project1"."EWM_MEASURE_ISSUE_TYPE_ACTV" AS "EWM_MEASURE_ISSUE_TYPE_ACTV",
"Project1"."EWM_MEASURE_ISSUE_TYPE_ORDER" AS "EWM_MEASURE_ISSUE_TYPE_ORDER",
"Project1"."EWM_MEASURE_ISSUE_TYPE_CLASS" AS "EWM_MEASURE_ISSUE_TYPE_CLASS",
"Project1"."MODIFIED_DATE1" AS "MODIFIED_DATE1",
"Project1"."MODIFIED_USER1" AS "MODIFIED_USER1",
"Project1"."MODIFIED_PROC1" AS "MODIFIED_PROC1",
"Project1"."APPL_ID1" AS "APPL_ID1",
"Project1"."EWM_ELEVATION_ACCURACY_TYPE_ID1" AS "EWM_ELEVATION_ACCURACY_TYPE_ID1",
"Project1"."EWM_ELEVATION_ACCURACY_DESC" AS "EWM_ELEVATION_ACCURACY_DESC",
"Project1"."EWM_ELEVATION_ACCURACY_ACTV" AS "EWM_ELEVATION_ACCURACY_ACTV",
"Project1"."EWM_ELEVATION_ACCURACY_ORDER" AS "EWM_ELEVATION_ACCURACY_ORDER",
"Project1"."MODIFIED_DATE3" AS "MODIFIED_DATE2",
"Project1"."MODIFIED_USER3" AS "MODIFIED_USER2",
"Project1"."MODIFIED_PROC3" AS "MODIFIED_PROC2",
"Project1"."EWM_ELEVATION_ACCURACY_CD" AS "EWM_ELEVATION_ACCURACY_CD",
"Project1"."APPL_ID3" AS "APPL_ID2",
"Project1"."EWM_ELEV_MEASURE_METHOD_TYP_ID1" AS "EWM_ELEV_MEASURE_METHOD_TYP_ID1",
"Project1"."EWM_ELEV_MEASURE_METHOD_DESC" AS "EWM_ELEV_MEASURE_METHOD_DESC",
"Project1"."EWM_ELEV_MEASURE_METHOD_ACTV" AS "EWM_ELEV_MEASURE_METHOD_ACTV",
"Project1"."EWM_ELEV_MEASURE_METHOD_ORDER" AS "EWM_ELEV_MEASURE_METHOD_ORDER",
"Project1"."MODIFIED_DATE2" AS "MODIFIED_DATE3",
"Project1"."MODIFIED_USER2" AS "MODIFIED_USER3",
"Project1"."MODIFIED_PROC2" AS "MODIFIED_PROC3",
"Project1"."EWM_ELEV_MEASURE_METHOD_CD" AS "EWM_ELEV_MEASURE_METHOD_CD",
"Project1"."APPL_ID2" AS "APPL_ID3",
"Project1"."ORG_ID1" AS "ORG_ID1",
"Project1"."ORG_NAME" AS "ORG_NAME",
"Project1"."ORG_ABBR" AS "ORG_ABBR",
"Project1"."ORG_TYPE_ID" AS "ORG_TYPE_ID",
"Project1"."MODIFIED_DATE4" AS "MODIFIED_DATE4",
"Project1"."MODIFIED_USER4" AS "MODIFIED_USER4",
"Project1"."MODIFIED_PROC4" AS "MODIFIED_PROC4",
"Project1"."ORG_TIN" AS "ORG_TIN"
FROM ( SELECT
"Extent1"."EWM_ELEVATION_DATA_READ_JRL_ID" AS "EWM_ELEVATION_DATA_READ_JRL_ID",
"Extent1"."EWM_ELEVATION_DATA_READING_ID" AS "EWM_ELEVATION_DATA_READING_ID",
"Extent1"."CRUD_TYPE" AS "CRUD_TYPE",
"Extent1"."CRUD_DT" AS "CRUD_DT",
"Extent1"."MEASUREMENT_DT" AS "MEASUREMENT_DT",
"Extent1"."ORG_ID" AS "ORG_ID",
"Extent1"."EWM_MEASUREMENT_ISSUE_TYPE_ID" AS "EWM_MEASUREMENT_ISSUE_TYPE_ID",
"Extent1"."EWM_STATION_ID" AS "EWM_STATION_ID",
"Extent1"."EWM_ELEV_MEASURE_METHOD_TYP_ID" AS "EWM_ELEV_MEASURE_METHOD_TYP_ID",
"Extent1"."EWM_ELEVATION_ACCURACY_TYPE_ID" AS "EWM_ELEVATION_ACCURACY_TYPE_ID",
"Extent1"."REFERENCE_POINT_ELEVATION" AS "REFERENCE_POINT_ELEVATION",
"Extent1"."GROUND_SURFACE_ELEVATION" AS "GROUND_SURFACE_ELEVATION",
"Extent1"."WATER_SURFACE_READING" AS "WATER_SURFACE_READING",
"Extent1"."REFERENCE_POINT_READING" AS "REFERENCE_POINT_READING",
"Extent1"."MANDATORY_READING" AS "MANDATORY_READING",
"Extent1"."COMMENTS" AS "COMMENTS",
"Extent1"."MODIFIED_DATE" AS "MODIFIED_DATE",
"Extent1"."MODIFIED_USER" AS "MODIFIED_USER",
"Extent1"."MODIFIED_PROC" AS "MODIFIED_PROC",
"Extent1"."COOPERATING_AGENCY_ORG_ID" AS "COOPERATING_AGENCY_ORG_ID",
"Extent1"."APPL_ID" AS "APPL_ID",
"Extent1"."SUBMISSION_DATE" AS "SUBMISSION_DATE",
1 AS "C1",
"Extent2"."EWM_MEASUREMENT_ISSUE_TYPE_ID" AS "EWM_MEASUREMENT_ISSUE_TYPE_ID1",
"Extent2"."EWM_MEASURE_ISSUE_TYPE_CODE" AS "EWM_MEASURE_ISSUE_TYPE_CODE",
"Extent2"."EWM_MEASURE_ISSUE_TYPE_DESC" AS "EWM_MEASURE_ISSUE_TYPE_DESC",
"Extent2"."EWM_MEASURE_ISSUE_TYPE_ACTV" AS "EWM_MEASURE_ISSUE_TYPE_ACTV",
"Extent2"."EWM_MEASURE_ISSUE_TYPE_ORDER" AS "EWM_MEASURE_ISSUE_TYPE_ORDER",
"Extent2"."EWM_MEASURE_ISSUE_TYPE_CLASS" AS "EWM_MEASURE_ISSUE_TYPE_CLASS",
"Extent2"."MODIFIED_DATE" AS "MODIFIED_DATE1",
"Extent2"."MODIFIED_USER" AS "MODIFIED_USER1",
"Extent2"."MODIFIED_PROC" AS "MODIFIED_PROC1",
"Extent2"."APPL_ID" AS "APPL_ID1",
"Extent3"."EWM_ELEV_MEASURE_METHOD_TYP_ID" AS "EWM_ELEV_MEASURE_METHOD_TYP_ID1",
"Extent3"."EWM_ELEV_MEASURE_METHOD_DESC" AS "EWM_ELEV_MEASURE_METHOD_DESC",
"Extent3"."EWM_ELEV_MEASURE_METHOD_ACTV" AS "EWM_ELEV_MEASURE_METHOD_ACTV",
"Extent3"."EWM_ELEV_MEASURE_METHOD_ORDER" AS "EWM_ELEV_MEASURE_METHOD_ORDER",
"Extent3"."MODIFIED_DATE" AS "MODIFIED_DATE2",
"Extent3"."MODIFIED_USER" AS "MODIFIED_USER2",
"Extent3"."MODIFIED_PROC" AS "MODIFIED_PROC2",
"Extent3"."EWM_ELEV_MEASURE_METHOD_CD" AS "EWM_ELEV_MEASURE_METHOD_CD",
"Extent3"."APPL_ID" AS "APPL_ID2",
**"Extent4"."EWM_ELEVATION_ACCURACY_TYPE_ID" AS "EWM_ELEVATION_ACCURACY_TYPE_ID1"**,
"Extent4"."EWM_ELEVATION_ACCURACY_DESC" AS "EWM_ELEVATION_ACCURACY_DESC",
"Extent4"."EWM_ELEVATION_ACCURACY_ACTV" AS "EWM_ELEVATION_ACCURACY_ACTV",
"Extent4"."EWM_ELEVATION_ACCURACY_ORDER" AS "EWM_ELEVATION_ACCURACY_ORDER",
"Extent4"."MODIFIED_DATE" AS "MODIFIED_DATE3",
"Extent4"."MODIFIED_USER" AS "MODIFIED_USER3",
"Extent4"."MODIFIED_PROC" AS "MODIFIED_PROC3",
"Extent4"."EWM_ELEVATION_ACCURACY_CD" AS "EWM_ELEVATION_ACCURACY_CD",
"Extent4"."APPL_ID" AS "APPL_ID3",
"Extent5"."ORG_ID" AS "ORG_ID1",
"Extent5"."ORG_NAME" AS "ORG_NAME",
"Extent5"."ORG_ABBR" AS "ORG_ABBR",
"Extent5"."ORG_TYPE_ID" AS "ORG_TYPE_ID",
"Extent5"."MODIFIED_DATE" AS "MODIFIED_DATE4",
"Extent5"."MODIFIED_USER" AS "MODIFIED_USER4",
"Extent5"."MODIFIED_PROC" AS "MODIFIED_PROC4",
"Extent5"."ORG_TIN" AS "ORG_TIN"
FROM "EWM_ADM"."EWM_ELEVATION_DATA_READING_JRL" "Extent1"
LEFT OUTER JOIN "EWM_ADM"."EWM_MEASUREMENT_ISSUE_TYPE" "Extent2" ON "Extent1"."EWM_MEASUREMENT_ISSUE_TYPE_ID" = "Extent2"."EWM_MEASUREMENT_ISSUE_TYPE_ID"
LEFT OUTER JOIN "EWM_ADM"."EWM_ELEV_MEASURE_METHOD_TYP" "Extent3" ON "Extent1"."EWM_ELEV_MEASURE_METHOD_TYP_ID" = "Extent3"."EWM_ELEV_MEASURE_METHOD_TYP_ID"
LEFT OUTER JOIN "EWM_ADM"."EWM_ELEVATION_ACCURACY_TYPE" "Extent4" ON "Extent1"."EWM_ELEVATION_ACCURACY_TYPE_ID" = "Extent4"."EWM_ELEVATION_ACCURACY_TYPE_ID"
LEFT OUTER JOIN "BUS_ADM"."ORGANIZATION" "Extent5" ON "Extent1"."COOPERATING_AGENCY_ORG_ID" = "Extent5"."ORG_ID"
WHERE (("Extent1"."EWM_STATION_ID" = 52370) OR (("Extent1"."EWM_STATION_ID" IS NULL) AND (52370 IS NULL)))
) "Project1"
ORDER BY "Project1"."EWM_ELEVATION_DATA_READ_JRL_ID" DESC
有问题的行是这一行（在查询中用星号标记，因为我无法将其加粗）。
"Extent4"."EWM_ELEVATION_ACCURACY_TYPE_ID" AS "EWM_ELEVATION_ACCURACY_TYPE_ID1"
如您所见，它在别名后附加了 1。我需要阻止这种情况或强制使用自定义别名。
我知道这是一个老问题，但对于必须使用旧 EF 和 Oracle 12c 的人来说可能是实际问题。但这是对我来说效果很好的解决方案：
public class InterceptorFixAliasesLength : IDbCommandInterceptor
{
public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
{
}
public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
{
}
public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
{
FixNameLength(command);
}
public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
{
}
public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
{
FixNameLength(command);
}
public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
{
}
private static void FixNameLength(DbCommand command)
{
var text = command.CommandText;
// Looking something like "AS "PARAMETER_1"" where PARAMETER_1 is the parameter name and length is greater than 30 characters
var pattern = @"AS ""([A-Z0-9_]{31,})""";
var matches = Regex.Matches(text, pattern);
var anyUpdated = false;
foreach(Match m in matches)
{
// if the alias is longer than 30 characters, generate a new unique alias
var paramName = m.Groups[1].Value;
if (paramName.Length > 30)
{
var newParamName = paramName.Substring(0, 27);
var newParamNameUnique = newParamName;
var i = 1;
while (text.Contains(newParamNameUnique))
{
newParamNameUnique = $"{newParamName}_{i}";
i++;
}
text = text.Replace($"\"{paramName}\"", $"\"{newParamNameUnique}\"");
anyUpdated = true;
}
}
if (anyUpdated)
{
command.CommandText = text;
}
}
}
public class MyDbConfiguration : DbConfiguration
{
public MyDbConfiguration()
{
AddInterceptor(new InterceptorFixAliasesLength());
}
}