Cardinatlity+Pairs

# Cardinatlity+Pairs - Implementing Relationships Patterns...

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Implementing Relationships -- Patterns and Rules These are the 16 possible cardinality patterns for a binary relationship along with the rule for implementing the relationship: (MinB,MaxB) (MinA, MaxA) Rules and Decisions (0,1) (0,1) Make a separate table or pick one direction to post only (depending on load) This cardinality pattern is rare in practice (0,1) (1,1) Post away from (1,1) (one minimum, one maximum rule) Post key of B into A (0,1) (0,M) If possible, post key of A into B (one-to-many rule) If this decision results in low load, make a separate table (0,1) (1,M) If possible, post key of A into B (one-to-many rule) If this decision results in low load, make a separate table (1,1) (0,1) Post away from (1,1) (one minimum, one maximum rule) Post key of A into B (1,1) (1,1) Post into (1,1) (one minimum, one maximum rule) Pick one direction to post only (1,1) (0,M) Post away from (1,1) (one minimum, one maximum rule) Post key of A into B (1,1) (1,M) Post away from (1,1) (one minimum, one maximum rule)

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Cardinatlity+Pairs - Implementing Relationships Patterns...

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