Class SQLDataSource

Method Details

• getTableColumns

  public List<String> getTableColumns()

  Returns List of column names from the underlying database table DataSource is bound to.

  This is based on the dbName, schema and tableName DataSource attributes to get the list of table columns. Note that the columns in returned list may differ from the DataSource fields as columns in database may have alternative names, there may be extra columns in underlying table or some fields may be missing in underlying table if they are using customSQL features at a DataSource level.

  If, for any reason, DataSource lacks the tableName attribute, getTableColumns() API falls back to returning the getDirectFields().

  Returns:

  List of column names from the underlying database table DataSource is bound to.

• getPartialWhere

  public static String getPartialWhere(DSRequest dsRequest, String... fieldNames) throws Exception

  Generates partial SQL condition expression for the fieldNames requested for use in the regular whereClause.

  The result is based on the criteria provided in DSRequest parameter and only criteria based on fields that are listed in fieldNames parameter will be generated, everything else will be skipped. If all fields are happen to be requested, then this method returns same SQL expression as is used in $defaultWhereClause Velocity context variable. If there's no criteria for the requested fields, then ('1'='1') will be returned.

  If you want a partial WHERE clause that excludes certain fields instead of naming all included fields, see getWhereWithout(DSRequest, String...). Also see OperationBinding.excludeCriteriaFields for excluding fields from automatic generation.

  If you are using aggregation, and you want to create a WHERE clause that applies to aggregated value, see getPartialHaving(DSRequest, String...) or getHavingWithout(DSRequest, String...).;

  Parameters:

  dsRequest - DSRequest to pick criteria from

  fieldNames - requested field names

  Returns:

  SQL expression filtered by requested fields

  Throws:

  Exception

  See Also:

  • getWhereWithout(DSRequest, String...)
  • getPartialHaving(DSRequest, String...)
  • getHavingWithout(DSRequest, String...)

• getWhereWithout

  public static String getWhereWithout(DSRequest dsRequest, String... fieldNames) throws Exception

  Generates SQL condition expression without the fieldNames requested to skip from the regular whereClause.

  The result is based on the criteria provided in DSRequest parameter and only criteria based on fields that are not listed in fieldNames parameter will be generated, everything on that list will skipped. If no fields are requested to skip, then this method returns same SQL expression as is used in $defaultWhereClause Velocity context variable. If all fields are requested to be skipped or there's no criteria after the skipping, then ('1'='1') will be returned.

  If you want a partial WHERE clause that includes certain fields instead of naming all excluded fields, see getPartialWhere(DSRequest, String...).

  If you are using aggregation, and you want to create a WHERE clause that applies to aggregated value, see getPartialHaving(DSRequest, String...) or getHavingWithout(DSRequest, String...).;

  Parameters:

  dsRequest - DSRequest to pick criteria from

  fieldNames - field names to skip

  Returns:

  SQL expression filtered by requested fields

  Throws:

  Exception

  See Also:

  • getPartialWhere(DSRequest, String...)
  • getPartialHaving(DSRequest, String...)
  • getHavingWithout(DSRequest, String...)

• getPartialHaving

  public static String getPartialHaving(DSRequest dsRequest, String... fieldNames) throws Exception

  Generates partial SQL condition expression for the fieldNames requested for use in the groupWhereClause (aka having).

  This is the same as getPartialWhere(DSRequest, String...) except that depending on operationBinding.useHavingClause setting it refers fields by either aliases or full SQL expressions, see OperationBinding.useHavingClause in the SmartClient Reference for details.

  Note that only fields that are selected in the main query may be used.

  Parameters:

  dsRequest - DSRequest to pick criteria from

  fieldNames - requested field names

  Returns:

  SQL expression filtered by requested fields

  Throws:

  Exception

  See Also:

  • getPartialWhere(DSRequest, String...)
  • getWhereWithout(DSRequest, String...)
  • getHavingWithout(DSRequest, String...)

• getHavingWithout

  public static String getHavingWithout(DSRequest dsRequest, String... fieldNames) throws Exception

  Generates SQL condition expression without the fieldNames requested to skip from groupWhereClause (aka having).

  This is the same as getWhereWithout(DSRequest, String...) except that depending on operationBinding.useHavingClause setting it refers fields by either aliases or full SQL expressions, see OperationBinding.useHavingClause in the SmartClient Reference for details.

  Note that only fields that are selected in the main query may be used.

  Parameters:

  dsRequest - DSRequest to pick criteria from

  fieldNames - field names to skip

  Returns:

  SQL expression filtered by requested fields

  Throws:

  Exception

  See Also:

  • getWhereWithout(DSRequest, String...)
  • getPartialHaving(DSRequest, String...)
  • getPartialWhere(DSRequest, String...)

• getSQLPrefix

  protected String getSQLPrefix(DSRequest req) throws Exception

  Override this method if you want to programmatically provide a prefix to SQL generated for this DataSource. Scan the client-side docs for sqlPrefix for details. Note, the default implementation of this method returns any operationBinding-level or dataSource-level declared sqlPrefix

  Parameters:

  req - Context DSRequest

  Returns:

  Query prefix text

  Throws:

  Exception

• getSQLSuffix

  protected String getSQLSuffix(DSRequest req) throws Exception

  Override this method if you want to programmatically provide a suffix to SQL generated for this DataSource. Scan the client-side docs for sqlSuffix for details. Note, the default implementation of this method returns any operationBinding-level or dataSource-level declared sqlSuffix

  Parameters:

  req - Context DSRequest

  Returns:

  Query suffix text

  Throws:

  Exception

• getSQLClause

  public static String getSQLClause(SQLClauseType clauseType, DSRequest dsRequest) throws Exception

  Returns the text of the generated SQL we will use to implement a clause of the supplied type for the supplied DSRequest. The clause text will be exactly the same as the value of the corresponding $defaultXxxxxClause Velocity variable that you can use when developing your own customSQL queries. Clauses consist of just the variable part and exclude the SQL keywords. The one exception to this is the special clause type "All"; if you specify this clause type, we return a full-formed SQL query suitable for passing straight to the executeQuery() or executeUpdate() method of a JDBC driver or equivalent.

  getSQLClause is not limited to the current DSRequest being processed: you can create a new DSRequest server-side and call getSQLClause() to retrieve the SQL that such a request would generate, which might be used as a sub-select in a larger overall query. This can be particularly useful with aggregated queries.

  Note that we ordinarily generate SQL that is self-contained and context-free, so you can store the clauses that this API returns and use them to construct a query for later execution without any dependence on the DSRequest. However, we are not always able to do this; binary columns and CLOBs cannot be assigned inline, so we have to generate SQL containing '?' markers, which can only be executed as parameterized queries. This in turn means that you need to store the values of any such fields in order to provide them as parameters when you come to execute the query.

  Also note that the query clauses produced by SQLDataSource are database-specific and will only work if run against the same database product they were generated for.

  Parameters:

  clauseType - The type of clause to generate and return

  dsRequest - The DSRequest embodying the fetch or update operation

  Returns:

  The text of the generated SQL we will use to implement a clause of clauseType for the supplied dsRequest

  Throws:

  Exception

• executeAsBatch

  public static List<Integer> executeAsBatch(List<DSRequest> dsRequests) throws Exception

  Convenience implementation of executeAsBatch(DSRequest[]), if you prefer to pass and return Lists instead of arrays.

  Parameters:

  dsRequests - List of DSRequests to execute as a batch

  Returns:

  List of update counts, each entry pertains to the corresponding (by ordinal position) DSRequest

  Throws:

  Exception

• executeAsBatch

  public static int[] executeAsBatch(DSRequest[] dsRequests) throws Exception

  Executes an array of DSRequests in a single JDBC Statement.executeBatch() call. The implementation builds up the batch by calling getSQLClause(SQLClauseType,DSRequest) to obtain the query text to execute for each DSRequest, and then adding each query with calls to Statement.addBatch(java.lang.String). This means that many of the sophistications of DSRequest processing are bypassed. Note the following:

  • No DMI, security checks, or other normal consequences of dsRequest.execute() will occur, because the DSRequests are not executed in the normal way
  • executeAsBatch() allocates and frees its own SQL connection, and does not participate in automatic transctions
  • However, the entire batch is committed or rolled back in a single transaction that is specific to the batch, assuming that the underlying database is capaable of transactions

  This method is intended to be used for edge cases where a large number of records must be updated, and the performance overhead of updating them singly makes normal DSRequest processing impractical. exeuteAsBatch() can give dramatic performance improvements in these circumstances, but at the cost of losing much of the functionality of a DSRequest.

  Parameters:

  dsRequests - Array of DSRequests to execute as a batch

  Returns:

  Array of update counts, each entry pertains to the corresponding (by ordinal position) DSRequest

  Throws:

  Exception