mysql强制索引和禁止某个索引

1、mysql强制使用索引:force?index(索引名或者主键PRI)

例如:

select?*?from?table?force?index(PRI)?limit?2;(强制使用主键)

select?*?from?table?force?index(ziduan1_index)?limit?2;(强制使用索引"ziduan1_index")

select?*?from?table?force?index(PRI,ziduan1_index)?limit?2;(强制使用索引"PRI和ziduan1_index")

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2、mysql禁止某个索引：ignore?index(索引名或者主键PRI)

例如:

select?*?from?table?ignore?index(PRI)?limit?2;(禁止使用主键)

select?*?from?table?ignore?index(ziduan1_index)?limit?2;(禁止使用索引"ziduan1_index")

select?*?from?table?ignore?index(PRI,ziduan1_index)?limit?2;(禁止使用索引"PRI,ziduan1_index")