[英]How to add header to csv table scala spark
我正在尝试从csv
文件中的表中读取数据。 它没有标题,所以当我尝试使用 Spark SQL 查询表时,所有结果都为空。
我曾尝试创建一个架构结构,虽然它在我执行printschema()
时确实显示,但当我尝试并且( select * from tableName
)它不起作用时,所有值都为空。 我也尝试过StructType()
和.add( colName )
而不是StructField
并且产生了相同的结果。
val schemaStruct1 = StructType(
StructField( "AgreementVersionID", IntegerType, true )::
StructField( "ProgramID", IntegerType, true )::
StructField( "AgreementID", IntegerType, true )::
StructField( "AgreementVersionNumber", IntegerType, true )::
StructField( "AgreementStatusID", IntegerType, true )::
StructField( "AgreementEffectiveDate", DateType, true )::
StructField( "AgreementEffectiveDateDay", IntegerType, true )::
StructField( "AgreementEndDate", DateType, true )::
StructField( "AgreementEndDateDay", IntegerType, true )::
StructField( "MasterAgreementNumber", IntegerType, true )::
StructField( "MasterAgreementEffectiveDate", DateType, true )::
StructField( "MasterAgreementEffectiveDateDay", IntegerType, true )::
StructField( "MasterAgreementEndDate", DateType, true )::
StructField( "MasterAgreementEndDateDay", IntegerType, true )::
StructField( "SalesContactName", StringType, true )::
StructField( "RevenueSubID", IntegerType, true )::
StructField( "LicenseAgreementContractTypeID", IntegerType, true )::Nil
)
val df1 = session.read
.option( "header", true )
.option( "delimiter", "," )
.schema( schemaStruct1 )
.csv( LicenseAgrmtMaster )
df1.printSchema()
df1.createOrReplaceTempView( "LicenseAgrmtMaster" )
Printing this schema gives me this schema which is correct
root
|-- AgreementVersionID: integer (nullable = true)
|-- ProgramID: integer (nullable = true)
|-- AgreementID: integer (nullable = true)
|-- AgreementVersionNumber: integer (nullable = true)
|-- AgreementStatusID: integer (nullable = true)
|-- AgreementEffectiveDate: date (nullable = true)
|-- AgreementEffectiveDateDay: integer (nullable = true)
|-- AgreementEndDate: date (nullable = true)
|-- AgreementEndDateDay: integer (nullable = true)
|-- MasterAgreementNumber: integer (nullable = true)
|-- MasterAgreementEffectiveDate: date (nullable = true)
|-- MasterAgreementEffectiveDateDay: integer (nullable = true)
|-- MasterAgreementEndDate: date (nullable = true)
|-- MasterAgreementEndDateDay: integer (nullable = true)
|-- SalesContactName: string (nullable = true)
|-- RevenueSubID: integer (nullable = true)
|-- LicenseAgreementContractTypeID: integer (nullable = true)
这是正确的,但是尝试查询这会给我一个只产生空值的表,即使该表没有填充空值。 我需要能够读取此表才能加入另一个表以完成存储过程
我建议按照以下步骤进行,然后您可以根据需要更改代码
val df = session.read.option( "delimiter", "," ).csv("<Path of your file/dir>")
val colum_names = Seq("name","id")// this is example define exact number of columns
val dfWithHeader = df.toDF(colum_names:_*)
// now you have header here and data should be also here check the type or you can cast
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