Class DB2zDialect

  • All Implemented Interfaces:
    ConversionContext

    public class DB2zDialect
    extends DB2Dialect
    An SQL dialect for DB2 for z/OS, previously known as known as Db2 UDB for z/OS and Db2 UDB for z/OS and OS/390.
    • Method Detail

      • initializeFunctionRegistry

        public void initializeFunctionRegistry​(QueryEngine queryEngine)
        Description copied from class: Dialect
        Initialize the given registry with any dialect-specific functions.

        Support for certain SQL functions is required, and if the database does not support a required function, then the dialect must define a way to emulate it.

        These required functions include the functions defined by the JPA query language specification:

        • avg(arg) - aggregate function
        • count([distinct ]arg) - aggregate function
        • max(arg) - aggregate function
        • min(arg) - aggregate function
        • sum(arg) - aggregate function
        • coalesce(arg0, arg1, ...)
        • nullif(arg0, arg1)
        • lower(arg)
        • upper(arg)
        • length(arg)
        • concat(arg0, arg1, ...)
        • locate(pattern, string[, start])
        • substring(string, start[, length])
        • trim([[spec ][character ]from] string)
        • abs(arg)
        • mod(arg0, arg1)
        • sqrt(arg)
        • current date
        • current time
        • current timestamp
        Along with an additional set of functions defined by ANSI SQL:
        • any(arg) - aggregate function
        • every(arg) - aggregate function
        • cast(arg as Type)
        • extract(field from arg)
        • ln(arg)
        • exp(arg)
        • power(arg0, arg1)
        • floor(arg)
        • ceiling(arg)
        • position(pattern in string)
        • substring(string from start[ for length])
        • overlay(string placing replacement from start[ for length])
        And the following functions for working with java.time types:
        • local date
        • local time
        • local datetime
        • offset datetime
        • instant
        And a number of additional "standard" functions:
        • left(string, length)
        • right(string, length)
        • replace(string, pattern, replacement)
        • pad(string with length spec[ character])
        • log10(arg)
        • sign(arg)
        • sin(arg)
        • cos(arg)
        • tan(arg)
        • asin(arg)
        • acos(arg)
        • atan(arg)
        • atan2(arg0, arg1)
        • round(arg0, arg1)
        • least(arg0, arg1, ...)
        • greatest(arg0, arg1, ...)
        • format(datetime as pattern)
        • collate(string as collation)
        • str(arg) - synonym of cast(a as String)
        • ifnull(arg0, arg1) - synonym of coalesce(a, b)
        Finally, the following functions are defined as abbreviations for extract(), and desugared by the parser:
        • second(arg) - synonym of extract(second from a)
        • minute(arg) - synonym of extract(minute from a)
        • hour(arg) - synonym of extract(hour from a)
        • day(arg) - synonym of extract(day from a)
        • month(arg) - synonym of extract(month from a)
        • year(arg) - synonym of extract(year from a)
        Note that according to this definition, the second() function returns a floating point value, contrary to the integer type returned by the native function with this name on many databases. Thus, we don't just naively map these HQL functions to the native SQL functions with the same names.
        Overrides:
        initializeFunctionRegistry in class DB2Dialect
      • columnType

        protected String columnType​(int sqlTypeCode)
        Description copied from class: Dialect
        The column type name for a given JDBC type code defined in Types or SqlTypes. This default implementation returns the ANSI-standard type name.

        This method may be overridden by concrete Dialects as an alternative to Dialect.registerColumnTypes(TypeContributions, ServiceRegistry) for simple registrations.

        Overrides:
        columnType in class DB2Dialect
        Parameters:
        sqlTypeCode - a SQL type code
        Returns:
        a column type name, with $l, $p, $s placeholders for length, precision, scale
        See Also:
        SqlTypes
      • getQuerySequencesString

        public String getQuerySequencesString()
        Description copied from class: Dialect
        Get the select command used retrieve the names of all sequences.
        Overrides:
        getQuerySequencesString in class DB2Dialect
        Returns:
        The select command; or null if sequences are not supported.
      • supportsSkipLocked

        public boolean supportsSkipLocked()
        Description copied from class: Dialect
        Does this dialect/database support SKIP_LOCKED timeout.
        Overrides:
        supportsSkipLocked in class DB2Dialect
        Returns:
        true if SKIP_LOCKED is supported
      • supportsLateral

        public boolean supportsLateral()
        Description copied from class: Dialect
        Does this dialect support the SQL lateral keyword or a proprietary alternative?
        Overrides:
        supportsLateral in class DB2Dialect
        Returns:
        true if the underlying database supports lateral, false otherwise. The default is false.
      • timestampaddPattern

        public String timestampaddPattern​(TemporalUnit unit,
                                          jakarta.persistence.TemporalType temporalType,
                                          IntervalType intervalType)
        Description copied from class: Dialect
        Obtain a pattern for the SQL equivalent to a timestampadd() function call. The resulting pattern must contain ?1, ?2, and ?3 placeholders for the arguments.
        Overrides:
        timestampaddPattern in class DB2Dialect
        Parameters:
        unit - The unit to add to the temporal
        temporalType - The type of the temporal
        intervalType - The type of interval to add or null if it's not a native interval