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In SQL, we have tables containing individual rows. Tables have strict schemas that every row must obey; there are columns with types and other possible constraints: unique, not null, value checks or references to rows of other tables. Referential integrity lies at the heart of this data approach - guarantee that if row B1 of table B references row A1 of table A, referred row (A1) must exist; orphan rows are not allowed. If we want to delete A1 row, there are two options:
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In 2009, PacBio published a paper expanding the principle into a full-blown sequencing technique. Once again, each nucleotide was labeled with a different colored fluorophore detectable by the ZMW to determine which base had been incorporated. The fluorophores were attached such that they would be cleaved off during the chemical reaction incorporating the base into the growing DNA strand; they would then diffuse out of the ZMW so that the next fluorophore could be detected. Sequencing took place on a chip with many wells simultaneously — a different type of parallelization where each well detected a single DNA molecule undergoing the same basic chemical reaction.。wps下载是该领域的重要参考
The former pharmacy worker also lost her spleen, battled pneumonia and developed gallstones which she was told might require further surgery.