Kalen Delaney's deep analysis of the Microsoft SQL Server family, the prestigious, in-depth study, is a glimpse into the complexities of SQL Server ladder and path. Have at hand
Microsoft SQL Server InternalsPhotocopy version, there are also
Microsoft SQL Server InternalsElectronic version, cross-reference, supplemented by practical exercises, benefited. But there is one place that is in contrast to the actual walkthrough. Microsoft SQL Server 2008/2012 Internals has this paragraph on page 272: This text, version 2008 and version 2012 is exactly the same. The text says that if you insert a full blank row into the table (except for the primary key, the nullable varchar fields are all null): INSERT INTO Nullvarchar (Col1,col2,col3,col4,col5,col6,col7,col8, COL9,COL10) VALUES (null,null,null,null,null,null,null,null,null,null); The actual storage in the data table exported through the DBCC PAGE command, whose NULL bitmap field is all zeros. The actual export results are as follows (SQL Server Express): Where the value of the NULL bitmap field is 0xfe07, which is actually equal to 0x07fe = 0000011111111110. The meaning of this value is: Except for the first field (the primary key field ID) is not empty, the remaining 10 fields are all empty. The Status Bits A = 0x10 = 00010000, where bit 4 = 1, indicates that the record contains a NULL bitmap field. Bit 5 = 0 indicates that there are no variable-length fields in the record, that is, because all variable-length fields are empty, SQL Server simply does not store the fields. Kalen Delaney's book in Microsoft SQL Server 2008/2012 Internals, why is the NULL bitmap domain all zeros?
Microsoft SQL Server 2008/2012 Internals A question
